Learn how to calculate the mean (average) number from a set of data
The revision cycle
Your revision will work best if you follow a cycle like this.
Don't spend too much time making flash cards without practicing actual question, but do take time to do this when you find you get stuck with certain questions.
Checklists can help you keep track of what you are confident at and what needs more work.
Revision guides are very useful as long as you are using them to help you tackle questions.
Science exams contain problem solving questions: It is not a good use of time to simply read the revision guides as this won't help you practice these skills.