I don't study Spanish, but I do A level French, so maybe you'll find this helpful?
To help me revise, the first thing I did was organise all my notes. I made topic sheets with specific vocab and phrases so that I didn't have everything everywhere in my folder. I also did sheets on verb conjugations and general agreeing/disagreeing phrases, negatives, superlatives etc. I'm not entirely sure how the Spanish exam is structured, but for mine we had to debate something (followed by sections about a region of France and French literature) so it was helpful to have all that down.
If you can, just participate in class discussion and maybe ask your teacher if you could have some practice with your classmates or even a couple of 1 on 1s with them.