Hey, I do maths, biology, chemistry and my best friend does history. Just started A2.
For maths, you don't really needs notes OR a revision guide. Just practice, practice, practice throughout the whole year. Do every single paper there has been, and then do them again until you get say over 90%+ right! Trust me, it works!
For chemistry, make sure you get a copy of the specification, and make notes on the specific information stated. It's all fun and games making notes from text books, but a lot of the time, about 80% of the stuff in there you don't need to know! It's the same with most text books, IMO.
Also with biology, get a copy of the spec, and make notes on each part of it from the exam board's text book. My teacher wouldn't allow us to make notes in class! (He has a unique way of teaching in that he believes making class notes is a waste of time, he'd rather lecture the subject and embed the information into each and every individual.)
Once you have a good grasp of most of the subject, start the past papers as soon as possible! A lot of the work in biology and chemistry, more biology, intertwine. I find the past papers are the best method of revision if you compare and analyse them, and learn the patterns of the answers in the mark schemes. You can know biology/chemistry inside out, but if you don't know how to answer the questions you can lose a lot of marks.
For history, I'd say go through the textbooks (make sure it's the right exam board!) and summarise information into key points. Learn how to structure the essay writing, and read back on examiner reports to know where people maybe missed marks on past exam questions. Infact, it's worth looking at the examiner reports for biology and chemistry too, you get a grasp of what the examiner is actually looking for in the answers.
Wow, that was a bit lengthy haha. Hope that helped though