Put large emphasis into studying for your 3+4 subject next year. (This does not mean you totally neglect your 1+2's, though - yes you need to pass, but more importantly you need good knowledge of units 1+2 to do units 3+4)
You don't want to be one of those people who say
"aww man I wish I did methods this year instead of last, I could've done so much better", just because you didn't understand the amount of work which must be done for a 3+4 subject to do exceptionally well.
If you are doing 3+4 methods in year 11, then I'm assuming you are rather talented at maths (the fact you also wish to do specialist the next year backs this up), so you shouldn't need much time to revise over all of unit 1+2, but still do some just in case.
Throughout the summer holidays I would advise starting the course. This doesn't necessarily mean doing all the questions which your teacher will set in the coming weeks (you can if you really want to...), but rather acquiring understanding of the given topics and reading them thoroughly (don't just skim over topics and think you have an understanding, this is a waste of time), so that future transition will be much easier.
In my opinion, the best thing you can do, both throughout holidays and the entire year, is successfully use the resources at your disposal. This forum offers great insight into the methods course and others alike, make sure you read through all the guides, notes, tips etc. (
here is a good thread for methods resources). Remember if a guide is for a different subject, this does not necessarily mean you can't make use of it. i.e.
Huaxiadragon's Experience in getting a 50 in Chem (Guide to How I studied)Furthermore, you should also use your teachers, tutors, friends and other people as well. Most likely you won't be able to be successful if you try and do everything by yourself.
Lastly, don't overestimate the amount of time you have (e.g. leaving study 'til the night before a SAC), do you're best and don't be lazy or you'll regret it!