I thought I'd share with you just a few tips I've picked up over the years of revision that hopefully might help :)
1. Organise yourself.
Do this before you even think about started to revise. Put your work into order, or into subject/module folders. Then you can see what you're missing and also how much you have to revise. This alone normally stops me from panicking too much.
2. Get what you need.
Folders, missing work, post-it notes, some comfortable coloured pens and some notebooks with lined paper.
3. Find your best way of revising.
People really do work in different ways. I personally like to get an overview of every single topic done first and as I do them, pin or stick them on my wall. This gives me a visual aid and I can see how much I have done. Some people prefer to keep everything in one notebook (or one for each module) or to fit everything they know about one topic onto one A4 side of paper. Mindmaps (however 'primary school' this may seem are normally quite good for most people).
4. Past papers.
Ask your teachers or lecturers for these if you can't find them online. They give you practice for the real exam as well as giving you a good idea of what might come up in the exam.
5. Test Yourself/Talk about it.
I find this is one of the best ways to get facts to stick in my mind after doing the outlines and past papers. Don't let yourself look at the work until you've given a question a good go, when testing yourself. Talk over theories you have to learn with your friends (even those who aren't doing the subject) as it helps organise things in your own mind and improves your explanation skills.
6. Don't overwork.
Don't expect to sit at your desk all day! You need breaks. Don't work for more than an hour at a time as your revision won't be as effective.
7. The day before the exam...
Drink plenty of water and go to bed as early as possible. Eat a good meal, a scrummy pasta dish is good if you can. Make sure you have everything you need for your exam (including a water bottle) ready in a bag by the door (one less thing to worry about) and read over simple summaries of work so you don't panic yourself.
I hope this has been of some use to you, Good Luck!