Make a load of essay plans for the main topics so you'll be prepared for whatever happens. Obviously you can't do this for every essay topic, but write a few at least and give them to your teacher to mark. Or you could just write a paragraph if whole essays is too time-consuming and give it to your teacher, as feedback is very important. Honestly use your teachers as much as you can, ask them how you can improve and get them to mark your work.
Other than that, try to remember analysis of the main quotes in your texts, always make yourself analyse quotes in multiple ways so your perspective seems more nuanced - for example, do two sets of analysis on a single quote; 1 where you name techniques and another where you link to big concepts and talk about metaphorical or conceptual meaning.
Make sure you're solid on main themes and symbols, and know your context!! Also try to research a bit more unfamiliar or unusual context, obviously examiners will get bored if they see the same context point written on every student's paper.
Good luck!