Still think you should start off with 3U jussayin
For 2U (I'm going to repeat what everyone else said)
1. Get either Fitzpatrick or Cambridge - either is fine (I would avoid grove/mif textbooks because they have a reputation for not being difficult enough)
2A. If you plan on doing the whole course before next year (would be fun/recommend lel) go in order of the chapters i.e. chapter 1, chapter 2, chapter 3...and then do the yr12 book
2B. If you plan on doing enough to get ahead (much more likely) find out what order your school does the topics in, and do it in that order stopping at the next test or next next test so you can focus on being awesome at that rather than being semi-good at everything.
3. For each chapter do questions, the way I do it in cambridge is I do a few of the regular questions to get a hang of the idea (tbh dont waste too much time here its usually very repetitive) do a majority of the development questions (they are true to their name) and do all of the extension questions. obviously if you are struggling with a concept/getting stuff wrong, do more questions.
4. past papers
5. win life