1) Research this board...there is a great deal of information in past posts.
2) Try to make yourself as "sellable" as possible, meaning doing extracurriculars and sports, having leadership duties, becoming a tutor, etc. (this is like applying to any college).
3) Get pharmacy experience. NOW! The more experience, the better. That way, you know for sure that you want to go into pharmacy since you would've seen what it's like. You can also learn a lot from pharmacists and develop good relationships (great for Letter of Recommendations...) Volunteer at a hospital pharmacy, and work at a retail pharmacy so you can have experience from both worlds.
4) If you're serious about pharmacy, then research the 2+6 schools that accept you as a pharmacist student in your freshman year. That way, you won't have to stress about getting in down the road.
5) Most importantly, but I'm sure you already know, make a good GPA (3.5+ to be safe) and a good PCAT score (90%+ to be pretty safe). However, not all pharm schools require a PCAT.
6) Develop some good study habits in high school. I never really had to study and got As and Bs. It's different in college! However, not all pharm schools require a PCAT.
7) If you want to get into pharm school after 2 or 3 years, you may want to consider going to community college to get your pre-reqs done. It'll save you money and can be easier (some people will disagree with me though...it's your call)
Just like what Binghamkid said, you can look at what schools' pre-reqs are on PharmCas.org. Most schools require GenChem 1-2, Biology, OrganicChem 1-2, Physics, Calculus, etc. on top of humanities electives.
Hope this helps. I know for a fact that I'm missing some other helpful tips. Just look around the forum like I said. Good luck!