Check out the GREs, GPA's, and acceptances thread at the top of the forum. People list out their stats and then say where they applied, if they got in, if they intereviewed, etc. It really helped me gauge where I was at.
**First and foremost... start shadowing as soon as you can. Keep a log of your hours and really picture yourself doing the work the PT is doing. Is this really what you want to do? What do you like? what do you not like? Check out a variety of settings. PT's work in multiple areas and their roles vary based on the setting they practice in. I started shadowing after my freshman year in college and I am thankful I did. I knew PT was where I wanted to be after that and focused on doing all i could to be an ideal candidate.
*search the websites of the programs you are interested. Check out PTCAS.org and look through their list of programs. if you click on the school it gives you a break down of the avgs of accepted students in that program (most of the time). *
Thats all i can think of. Good luck! The fact you are thinking about this now means that you will be well prepared in the long run!