While you're writing there are things you need to watch out for, repetition is one of them. While reformatting one of my older books to create an ebook version I noticed how many of the chapters began with 'I'. It was a very headdesk moment. I cut myself a little slack because it was the first book I ever wrote and it was way back in 2010. It needs to be fixed though. 

There's an entire list of dreaded words you should attempt to avoid using or overusing.

I

Had

Just

So

Very

Like

That

And

Then

But

Of

Some

Like

Simply

These words are considered filler words, and most of the time,e a sentence will read fine without them. While using some of these words is unavoidable at times, try not to overuse them. 

Let's see an example-

We really had to go to the grocery store. All we had left were two cans of beans and a couple of rotten tomatoes. I was starting to believe we just might starve to death if we had to go any longer without food. It was time to suck it up and make that trip to the store, I just needed to make a list.

Once you establish that you 'had' something, you don't have to repeat it. Just was used too many times. Let's go through this paragraph and see how we can rewrite it.  

Rewrite-

We needed to go to the grocery store. I looked into the kitchen cabinets to discover, all that stared back at me were two cans of beans. The fridge contained two shriveled, rotten tomatoes, which was no help. There was a real possibility of starving to death if we went without food any longer. I grabbed a piece of paper to begin scribbling out a list, it was time to suck it up and head out to the store.

The words you choose make a big difference in how things read. There is no reason for most of those filler words. If you can write a sentence without them, then do it. Always look for an opportunity to word a sentence differently. 

There's an editor I know who hates sentences that begin with 'ing' words. There are pros and cons to beginning a sentence this way. If you Google it, you can find more in-depth explanations about it. It honestly doesn't bother me. I've read books that begin sentences with 'ing' words.

Don't overcomplicate your sentences with unnecessary words. It tends to make you sound pompous or as if you're using them so you sound smarter. If it comes off to readers as sounding forced they aren't going to want to read it. 

Avoid things like "I literally died when I saw it!" If your character literally did something then they actually did it. If they literally died, then they're dead and gone and speaking to you from the afterlife. If you use literally then it happened. When you use that word, then it occurred in a literal sense; it is exact.

Editors will knock you for using it unless something did happen.

"She literally walked into the wall because she was too busy watching her crush walk past." It happened, so literally works in that sentence. However, your word processor's grammar check will likely tell you not to use it.

Always double-check yourself and be certain that what you're writing makes sense and is accurate.