In my opinion, the best revision starts in the classroom. That is, if you don't understand something: ask questions! You don't want to be just listening to a teacher drone on, or even just following along in your textbook. You want to be actively participating. Take notes as you go, if you miss something or don't quite understand, ask your teacher to repeat it. Then see if you can create an analogy that helps you, personally, to understand a concept. It doesn't matter if they're stupid, if it helps you remember, go for it. For example, I created a couple of Biology pick up lines, which were horrendously cringeworthy and not recommended for public use, but were factual and stupid and made me giggle so I remembered them.
Secondly, find out if your teacher has any kind of policy for after school hours help. Do they check emails, are they willing to meet up with you at lunchtime, etc. My teacher gave the class his phone number, and was bombarded with calls around exam time, but was happy to help.
With revision, you can do summaries, but I find the best help is doing questions. And when you inevitably reach a question you don't understand, or know how to answer but don't know why its correct, write that down in a separate notebook. That way, if you do arrange a meeting with your teacher, you know exactly what concepts you need to cover.
When it comes down to it though, the exams are all about analysing the question and figuring out what on earth the assessors are looking for. Get a highlighter. One that is disturbingly bright. Highlight key terms, and do lots and lots and LOTS of practise exams, because that's probably the best preparation. You'll soon find common themes, and don't rush through reading the questions! They're tricksy, and confusingly worded. But all you really need is common sense. They're never going to ask you about something you haven't learnt. You just need to relate things back to what you know
