When I’m tutoring, I frequently have conversations along these lines:

“Is there anything particular you would like help with today?”

“I need to revise for a test.”

“What do you need to work on?”

“Everything we’ve done this term.”

“What have you covered this term?”

“I can’t remember.”

To avoid this situation, my advice is to keep an index.  For every subject that you study, write a list of lesson dates and the topic studied in that session.  This can be kept in the front of your notebook or folder and quickly updated during each session.  You could even go as far as to include page numbers.  That way, you have an easily accessible overview of topics studied, which you can also use as a revision checklist.

This is a quick and easy hack that can save time in the long run and help you to prepare more effectively and confidently for tests and exams.