Depending on how well you did, you may want to consider a SAT prep course. Also, the December holiday break is a great time to get the real scoop from your college friends who are home on break. It is also a great time to make plans to visit them during your spring break. It is also time to find out the school's deadline for applying for admission. February - Start researching scholarships.
Scholarships equate to free money.
There are many sources available through your library, guidance counselor's office and the Internet. Take your AP exams, SAT I, and SAT II tests. May - Eliminate any surprises. Check your transcripts and make sure you have the right credits you need to graduate from high school. Investigate summer programs for high school students at a college you're considering.