I suppose most of the people here are followers of mine and are aware of the fact I write Maze Runner fanfics. There exists an amazing story with a LOT of writing tips for Maze Runner fics. Pretty sure it's written by stilestastic.

But, these are general things I think are nice to know:

Capitals:

All the jobs need capitals (Runner, Builder, Slicer, Bagger...).

The places in the Glade and the Glade itself (the Maze, Homestead, Deadheads, Blood House...)

I would recommend writing either w.c.k.d., WICKED, or WCKD, but not wicked.

And obviously at the beginning of your sentence and names!

Personality:

Yes, Minho is a sarcastic, funny character. But that doesn't mean he can't be caring or rude or sad or angry! Don't turn him into a whole different person, but do allow him to have other emotions.

Make sure to describe his biceps, though.

Newt. Is. Not. Always. A. Cutie. He. Can. Be. Angry. And. He. Had. An. Attitude. In. The. Books.

I always have the urge to make Thomas a dumb character, but more with "act before thinking" and not the "he doesn't know maths".

Because he does, trust me. That boy is super smart, just not with his actions (nor plans).

So try not to make him the school kind of dumb!

Okay, I have to admit that my younger self made Gally the bad guy in my first book (Unique), but after that I kind of realized he could also be the OC's friend (Redamancy/Love Lessons/Hiraeth), or he at least isn't sexist/a blamer/always angry.

It's optional, but you can try to have your OC to (attempt to) understand Gally. Maybe even let the OC agree with him!

I think Fry is usually portrayed well, but he often gets forgotten. I've got to admit that I have too, especially because the movies didn't give him many lines and that doesn't give me much ideas of what he's like. He's funny, kind, and can make good jokes, right...?? That's how I write him, at least.

Okay I have no idea what else to say, but I'll publish a part II of this if I do!