Past papers! Taking past papers and then finding areas within a topic you don't understand rather then the whole topic will save you time because there is no point in learning the stuff you know already. Time yourself taking one and if you don't finish in the given time then that is also area to cover but don't worry if you keep taking them it should be really easy once summer hits. (That's if you start now Christmas time)
I have a past paper tracker for each module within the whole subject (got it of Tumblr) that I stick at the front of my binders. This helps me track my progress as I can write how long it took me to take each exam, the grade I got if it were a real exam, how many more marks I would need to get my goal grade (be realistic with this) and topics to go over before attempting another exam, this allows me to see where I am improving but also where work still needs to be done.
All the areas or even topics you didn't do well in, write some key questions or facts on a flash card (Or even a summary of the date or term etc) and get members of your family or even friends to test you. Then a week later retake the test or a different on of the same subject area and compare marks.
When you get home after college or even for an hour at the weekend rewrite your notes ether on a laptop/computer or handwrite than, going over the same information twice will help you retain the information.
I also find colour coding works, I have four different colours for your 4 A levels and use the colours for binders, flash cards, highlighting key words ect. I don't know if it will work for everyone but i find it a lot easier to remember information via colours.
Last but not least sleep and water. If you aren't getting enough sleep or drinking a least 2 litres of water a day you won't be able to retain all the information you are revising so there would really be no point.
I hope this all helps and good luck revising.