One of the things that drives me nuts personally is hamhanded exposition. You know the stuff. Where the writer feels like you have to know every single detail of a character past as they talk with someone they just met, or you see the vingette of their flashback as voice over comes in. Or worse, it's just the character themselves talking, and talking, and talking, about how they feel that moment, or how this happened or that. Case in point: Attack on Titan.
How do you fix this?
1. Hold back.
2. Listen to conversations and think about the times people have told you about their past.
3. UNDERSTAND WHAT PEOPLE DON'T SAY HAS MORE WEIGHT THAN SPELLING IT OUT.
Outside of that...hyper-sexualization OR the blatant excuses people use for hypersexualizing characters. I read a comic recently that had one female character defending another's distaste for any clothing at all as a "Well clothes make it harder for her to fight in..." NO. No. No. I'm sorry but gymnastics without a bra on hurts, and prolonged running in heels will screw up your back and feet beyond repair.