Outlines are, I think, one of the most important things in creating a book

Without an outline, you can forget things, you can get lost in your own plot, you can get stuck

I use Milanote to make most of my outlines. It's incredibly helpful.

It helps me keep track of my OC's and plots and stories. These are the only ones I've got right now, because i only recently found it.

it can help you sort out how you want the story to go. As you can see in this above picture, I've compiled character lists sorted by age. It helps me when I'm trying to pick a character for a certain action. I've also got the entire timeline of my story on the right, and each individual card has a bunch of information about that part of the book

character profiles are super easy to make, and it helps to come back and see all of the information you compiled about your character

another thing; a lot of people say that outlines have to be serious and well thought out.

those people are wrong.

make your outline funny. abbreviate. bullet point. use inside jokes only you understand. add little sarcastic tags. capitalize random things. don't capitalize anything. cuss. exaggerate words. your outline is for you, and keeping it lighthearted and happy can actually help motivate you to write!

for example, I'm currently working on a rewriting of the Harry Potter books, and this is some of my outline for the events of the first book put into a few chapters

make shit stupid, it's only for you anyways

you don't need detailed ones. mine was actually fairly detailed, although it might not seem like it. each bullet point listed the things that would happen in those chapters more in-depth than a normal general outline would do

it's okay to have a general outline. it's okay if your outline is just 

Chapter One: Open in the middle of action scene. (Explain how they ended up there in several chapters)
Chapter Middle-somewhere: love interest will come into the cafe they work in and order a coffee that the barista (mc) completely fucks up but love interest just laughs
Chapter somewhere-after-middle: fucking up coffee becomes an inside joke??
Chapter angsty part??: love interest is kidnapped by bad guy from chapter one
Chapter end??: happily ever after (no kids tho fuck them kids)

like that was fairly generic, but it tells you where your story is going, even if it's vague

More than anything, KNOW HOW YOUR STORY IS GOING TO END

if you don't know how your story will end, you won't know how to get there.

and that's where a lot of people, myself included, can get stuck. I've started a story without knowing how I would end it, and it was just upsetting and stressful

make an outline kids :)