This is how to write a romance that won't make your readers roll their eyes, puke, or want to strangle you. (Many of these bolded lines are quoted from other users, so it's not all my own material.)

1. A true love = BEST best friend.
The most important rule of romance: you can't love someone that deeply unless they are your best friend first. You have to be able to laugh with them, relax with them, cry on each other's shoulders, and just all-around enjoy their company.

This doesn't mean you do the cliche i-fell-in-love-with-my-best-friend deal. It means they need to become best friends over the course of the story before developing strong feelings for each other.

2. Love at first sight is a ridiculous and impossible concept.
If you fall for someone the moment you look at them, you're falling for their appearance. That isn't love. That's lust and infatuation. That's a physical attraction. It's alright if your character feels attracted to their potential love interest at first (though try to avoid this! It's considered cliche and predictable if done incorrectly), but they have to learn that there is more to the person than what they first thought. They could even fall out of "love" when they see how terrible the person really is, and then really learn to love them as they share more experiences together.

3. Romance should never be the #1 focus of your novel, even if it is a romance novel.
Sounds crazy, right? Romance novels means it's about romance, doesn't it? Nope. Two people learn to love each other because they shared some kind of deep/touching/horrible/traumatic experience with each other. Let me reiterate that: PEOPLE FALL IN LOVE THROUGH SHARED HARDSHIPS. This is where the conflict in your story comes. No, the conflict is not, "Oh, no! I'm all alone and lonely and no one likes me, but that one hot guy is especially mean to me. I'll just act all snarky/needy toward him until we both fall madly in love with each other for the rest of eternity." If you don't see what's wrong with that, I will slap you with a wet fish.

There should be some real conflict happening to drive your plot, and it's through that SHARED EXPERIENCE OF HARDSHIP that your characters fall in love with each other. Again: they need to be friends before they become lovers. Conflict could be anything from here to the moon. The MC could be caught in a war, have lost a friend, killed a friend, hurt someone important to them, was hurt by someone, out for revenge, etc. The main point I'm trying to make here is that romance is not a conflict. The conflict of your novel (romance novels, too) should never be anything to do with romance. Romance is a result. Not a goal.

4. Know the difference between "protective" and "abusive".
One partner could of course be abusive in the relationship, but please don't try and portray that as romantic. A guy (or girl) forcing their girlfriend (or boyfriend) to stay home and not see her friends by disabling their car is abuse. Please portray it as such.

5. Please, please, please, don't describe the love interest as good-looking/handsome/sexy/wonderful/hot or any other synonym of those.
Unless there is a legitimate reason for them to be good looking that is relevant to the main conflict of the novel (which, remember, is not romance), please don't fangirl over him/her within the novel. Oscar Wilde's The Picture of Dorian Gray handled a smoking hot protagonist the right way. Because he was so good looking, an artist had Dorian model for a portrait, and that gets the plot going.

Do any fangirling of your characters on your own time, not ours. We don't fall in love with looks. We fall in love with personality. Making the love interest really good looking and fawning over them in the narration just turns the romance shallow and superficial. It makes us believe that the MC fell for them just for their looks. This is lust/infatuation, not love.

6. Life is not usually a Disney princess movie.
This goes with love at first sight. In most older Disney princess films, the main characters fall in love after one catchy song. Aladdin is how not to do it. Mulan is how to do it. Allow me to explain:

Aladdin: Jasmine originally falls for Aladdin when he pretends to be a prince and takes her on a magic carpet ride. After the "Whole New World" song, they're cuddling and holding hands. Again, if you don't see what's wrong with this, I will slap you with a wet fish.

Mulan: Mulan gets ragged on by Shang, but she's determined to prove that she can be a soldier that he can be proud of. As I mentioned above, the main conflict of Mulan (at the "I'll Make a Man Out of You" song) is that she's trying to hide that she's a woman while training to become a soldier in the Chinese army. It's not that she's attracted to Shang or wants to get with him. For most of the movie, there are no romantic feelings between the two at all, and their love blossoms gradually, through the trauma they face together. Mulan's initial goal is to prove herself to Shang, not to fall in love with him.

See the difference of a realistic relationship versus an INSTA-LOVE relationship?

7. The love interest should have flaws, and the MC should accept them and love them not regardless of their flaws, but because of their flaws.
One of the biggest mistakes I see with today's romance is that the love interest has no real flaws or the MC pretends the flaws don't exist. The person is described as perfect and wonderful and awesome. There is no such thing as a "perfect" human being.

Likewise, don't have the love interest be a complete bad boy with absolutely no redeeming qualities other than his big muscles and dreamy eyes, and then two pages later, the MC is making out with him and declaring their love for the person who has no redeeming qualities. Balance out the flaws with the strengths. Extremes can be done, but those tend to become one-dimensional if done by a novice writer.

Real people have annoying flaws. If you have problems with the other person (and realistically, you WILL have problems with the other person), you have to work it out with them. Don't dismiss them and let their movie-star good looks blind you to them (unless of course, that's the point of your book and you're satirizing this). Flaws should not be ignored. They should be taken into account, dealt with, and accepted. Sometimes a character will try to change their flaws for the sake of the other person's happiness (quitting smoking, for example). That's awesome, just don't go overboard. Some flaws can never be fixed, remember. I'm an introvert and get really shy around people, and that probably will never change.

Also, never, ever have your MC change herself to win the heart of her love interest.... NO. Save me the effort of hitting you with another fish. (Again, unless that's his/her character to try and please others, but it shouldn't work out well in the end.) You've all seen the storyline where the nerdy girl gets a makeover to catch the hot guy's attention, and in the end he admits he loved her nerdy self all along, yadda yadda yadda. We see that trope so often because it actually has validity. The only time your character should change themselves is to give up an unhealthy habit that causes harm to themselves or others (such as quitting smoking so their child doesn't breathe in 2nd-hand smoke and so they don't get cancer), sacrificing something for the other person's benefit (see the how-to chapter on sacrifices for more on this!), or if you're going to write it with the moral that this character made a poor decision and endured some consequence because of it. They shouldn't change the flaw just so the love interest doesn't dump them.

Another example: Mulan wanted to become a stronger warrior for herself, not for Shang (though she did want him to accept her, which is different from a romantic motive).

8. “I'm selfish, impatient and a little insecure. I make mistakes, I am out of control and at times hard to handle. But if you can't handle me at my worst, then you sure as hell don't deserve me at my best.”
― Marilyn Monroe

9. How they fall in love and if they fall apart isn't in how they met, or anything. It's just in who they are.

10. It's all about sharing and giving of yourself for what's best for the other person, although you have to respect yourself at the same time.
Don't have your MC go completely mindless-zombie-slave mode for the other person. He/she should still have their own head and not completely throw themselves at the other person. Love is SHARING yourself with someone else. Not GIVING yourself to someone else. SHARING IS CARING. :D

11. "Immature love says: 'I love you because I need you.' Mature love says: 'I need you because I love you.'"
- Eric Fromm

12. Don't have your MC keep switching love interests every other chapter.
Please don't. It's nauseating, to say the least.

13. A continuing rant on INSTA-LOVE...
People do not fall in love in a day, or a week, or a month (okay, I'm guilty of a month with two of my charries.... *cough* I'm working on it). It takes time. Lots of time!! Don't have them declare their undying love for each other a week after they met. It's not realistic, and you end up getting a very co-dependent relationship. Your charries should not just depend on each other (unless of course, they're in an enemy war zone and the only person they feasibly CAN trust not to chop their head off is one another). 80% self-reliant, and the other 20% gets divided between several people: the love interest, friends, family, acquaintances. Heck, there's some dependency on the mailman, don't forget (how else will you get your snail-mail?). You can't base your entire life on just one person. Life is a network of relationships, so please don't forget about the rest of them.

14. Awesome quote!!
"I spend most of my time trying to figure out what the formula of a great romance is. Witty, unfogettable dialog like Jane Austen? Terrible Dilemas like Megan Whalen Turner? Problems like Lois McMaster Bujold? Utter devotion like Jim Buther's Harry Dresden? What I finally figured out was that there is no formula for a true romance. The trick to making a reader believe that the two characters will fall in love with each other is to make the readers fall in love with both characters. How do you do that? You make the characters deeply good then throw them into an impossible situation. They will find each other. I think the people like that really do, in real life. The best romance is one that is utterly unique and that would fit no one else. After all, who could love and live with someone like Chala? Only Richon. But that doesn't mean it'd be easy."

-Mette Ivie Harrison, author of The Princess and the Bear.

15. On appearance and physical beauty...
After you fall in love with someone, they usually end up looking much more attractive than you perceived them to be before you fell for them. People look "hot/gorgeous" because you're in love with them, even if they were an ugly bat before. Falling in love with someone usually makes them more physically attractive to you. I remember this one guy from high school wasn't very good looking. Then my brain decided to have a horribly large crush on him. After that, I thought he was smoking. My friends (being the oddballs they were) rated him a 4/10 on the hotness scale. So looks really don't matter. You fall for the personality, not the appearance.

This is a quote from the "Awesome Quotes" chapter in this guide, but I thought it's very important, so I'll repost it: “When you start to really know someone, all his physical characteristics start to disappear. You begin to dwell in his energy, recognize the scent of his skin. You see only the essence of the person, not the shell. That's why you can't fall in love with beauty. You can lust after it, be infatuated by it, want to own it. You can love it with your eyes and body but not your heart. And that's why, when you really connect with a person's inner self, any physical imperfections disappear, become irrelevant.”

16. The biology of "love at first sight".

No matter how much you want to deny it, love at first sight is simply just a biological mechanism that has evolved (think Darwinian evolution) to increase the fitness of the human race.

Before we delve into romantic relationships, where else do we see the concept of love at first sight? Newborns! Any mother would tell you that they loved their baby the moment they gave birth to them and saw them. But why? Newborns are actually quite ugly. They're screaming. They just broke your hip bone and put you in unbearable agony for the past few hours (or days!).

When a mother gives birth to a child, her brain (the pituitary gland, to be exact) releases a lot of a hormone called oxytocin. Oxytocin is known as the "bonding hormone." It makes the mother fall in "love" (maternal love) with their baby so they won't abandon them.

Love at first sight may also have to do with oxytocin. It's an established fact that when you have sex with someone, a lot of oxytocin rushes through your body, so you automatically fall in "love" with them. (Generally.) Evolutionarily speaking, this happens because it's more likely for a baby to survive if they have two parents to keep it safe. Your body would want you to fall "in love" with the person you just "mated" with so you both stay together. (for a refresher of Darwinian theory: all organisms evolve in order to increase their chance of survival to produce viable offspring. Why/How this happens is a long story, which I won't go into now. For our purposes here, just remember "survival of the fittest". Those with the traits best suited to their enviornment are more likely to survive and pass on those traits to their offspring.)

Oxytocin-induced love isn't TRUE love--as in loving the person for who they are (how can you have any idea who they are if you just met them two seconds ago?). I'm guessing your brain releases oxytocin when you see someone who can be a potential mate, which is why you become attracted to them. It's your body's chemistry that's making you overrun with loving emotions. If your love can extend past that oxytocin/hormonal rush, THEN you can call it true love.

Also, it's note worthy to point out another mechanism of WHY you are attracted at first sight to some people over others. Get that notion of HE/SHE'S MY SOULMATE AND FATE BROUGHT US TOGETHER out of your head.

Think about the hottest guy/girl you can. What do they look like? The guy would probably be tall and buff (or at least, not obese/frail/sickly). The girl would probably have a tiny waist, big hips, and big breasts. Stuff you see in the media all the time, yes?

But why are we attracted to that certain body type? Why aren't obese people attractive to most of us? Why are some people "ugly" and some "gorgeous" to us? (This is different across different cultures, of course, and I'll just be focusing on American culture and ideologies.)

Let's explore a bit of history, shall we? Back in the day (think thousands of years ago to the first humans), most people lived as hunter/gather societies. The males would generally go off to hunt for food while the women cared for the young and gathered fruits and veggies. Hunting took a great deal more energy and athleticism than picking berries from a bush. The male had to be in good shape to get food for their families. This is why females are more sexually attracted to buff, muscular guys rather than fat, lazy ones. It's biologically hardwired into our brains, because that's how we evolved. Even today, an obese person would probably have a plethora of health problems, which can't be good for the health and safety of the family.

Vice versa, long, luscious hair on women signifies fertility, which is why in today's society, girls tend to have longer hair than guys. Also, wide hips (or a big butt) means they'll have less trouble delivering the baby during childbirth, and big breasts means they can breastfeed properly. This is why guys generally find girls with big breasts and big butts "hot".

So my point is that "love at first sight" is simply a biological mechanism, not actual you-are-my-soul-mate-other-half-who-completes-me love. A relationship like that takes a lot of time to build. (And if you still aren't sold, wouldn't your story be much more satisfying if your characters had to WORK at a relationship and build it rather than just POOF! They're in love. Where's the fun and suspense in that?) Again, physical attraction can be the initial stage of the relationship, but getting past that would usually be considered true love.

Trust me, guys, love at first sight is a myth, not real. It can quickly become something real, which makes us believe that it initially was real, but you can't love a person whom you know nothing about other than what they look like. That is infatuation and lust. I repeat, that is infatuation and lust, not true love.

17. "There's a difference between being genuinely in love with someone and being in love with the attention they give you."