Depending on exam board (english literature), context is a big deal so learn about the lives of your authors and their motivations for writing. The author's contemporaries should be your next stop, and scholarship about the authors, particularly where it relates to themes in the novel.
Learn Shakespeare quotes, and depending on the specifics of your papers different productions and critical views of them. Also, do lots of practice on close analysis (picking out how exact words can influence a sentence/passage).
In general though, mark schemes as mentioned by PPs, also befriend the teachers as much as you can. Don't be a snake to others, but be a good student, always be polite, no attitude, etc. Two benefits to this, one if you don't do the homework they're less likely to rip your head off, two if you need to ask a question or need some support they're a lot more lenient. Go to the bulk.of lessons too, my attendance wasn't perfect but unless you're ill be in the lesson.
In terms of organisation, have a seperate file for each subject, and in my case I found it very useful to have one for each paper which kept all of my notes and past papers in. File everything away the day you get it, at the end of the lesson if possible. If homework is set start it as soon as possible, unless it's something that will take a while in which case I would recommend waiting until the weekend, but most things do them on the night. Learn when the library is quiet which will be good times to work. The thing my economics teacher told me which I found most helpful was take at least one day (for me usually sundays) where you don't worry about school work, it kept me sane first year.
The biggest thing is to trust yourself, his grades will drop at the start, they all do, but if he works hard and does everything he should they will pick up.
Also, I know this seems very overwhelming but you don't have to do all of this at once, implement things slowly over time and he'll be fine.
For reference, I got AAAB (one mark off AAAA) plus a B at geography AS (which I dropped), and came top of my year for Geography and Economics, plus got 95% and 100% for two of my Classics papers.