I took the June test last year and got a 166. I only did 20 PTs and nothing else. Right now, I have 56 preptests. could anyone give me some advice on what other materials I should definitely get? I am not a native English-speaker, are there some books, or periodicals you guys recommend me to read?
I've done 10 preptests in the past two weeks and the scores range from 162 to 175

I'm really frustrated right now and don't know whether the efforts will be paid off.
Thanks!