It might be worth trying the new method of being creative and making your own PowerPoint Presentations and many people in year 11 are also sharing their revision notes and creating their own revision guides.
You could always write an essay on each of the different topics,without a revision guide,about what you know on the topic and then find out what you don't know and revise it because this method will stop you wasting time on things you know and understand.
I would also advise you to focus on the AS level because A-Levels are a lot harder than GCSEs and you could easily get embarrassing grades that you will drag with you for the rest of your life if you don't put the effort in now.
Err this videos got a couple decent tips in terms of revising. Especially the syllabus tip (tip 3 i believe) and its not a boring video to boot.
On top of that , i'd say make sure you keep hydrated and walk around every now and then whilst revising, keeps the blood flowing and increases work output!