1. Once you know how, do tell me.
Though not to sound like a douchebag; being overconfident comes naturally, even to not-A graders who get a good score in a test a few too many times. The only help is to keep reiterating to yourself that you cannot maintain your grades if you do not study. Also, develop the urge to outdo other students doing better than you or, if you are the topper, keep the desire to be on top. When you will be fearful of losing your position you are more likely to keep studying for tests and even the final exams.
2. Study. There is no other way
And I'm quite serious. If you've done AS you already know the drill and the effort; and it seems it worked for you. So keep it going this year and learn from your mistakes so that you can reciprocate good results.
3. Three months is a good time: firstly, you should buy a SAT Study Guide by a good publisher, like Barrons. Following it alone should help you get a good SAT score. The key to SAT, however, is not just practice but good memory of the vocabulary lists combined with English language skill, so along with practicing the SAT papers and the like, learn the vocabulary list and start early so that you can do it twice and incorporate it in your day-to-day conversation, eventually making it come naturally to you.
Hope it helped <3
