Best way to improve a 33?

I’ll be taking the ACT somewhere in March or April (when my school offers it). I took the ACT in September without any prep, got a 33, with 28 on English, 34 on Math and Reading, a 35 on Science, and a 26 on writing. I’d like to raise it to a 35 or 36, but not sure if I should just focus on English or all four sections. I’ve ordered the Princeton Review book and will buy the ACT one once the newest one will come out. Should I get any other books? Also, my writing score will probably go up, since from September I’ve been in AP Lang, but what is a good score on the writing section?