If you athlete is considering wanting to compete in college there are several things you should know and several things you have to do. It is never too soon to plan, starting your freshman year in high school.

Requirements to attend a NCAA DIV 1 school :
4 years of English
3 years of mathematics (Algebra I or higher)
2 years of natural/physical science (one must be a lab science)
1 year of additional English, math or science
2 years of social studies
4 years of additional core courses (from any area listed above, or from foreign language, nondoctrinal religion or philosophy

NCAA Initial Clearing house - requirements, and a ton of other informations, including how to register for your intial eligibilty (should be done summer after Jr Year)
Dyestat's Scholar Athlete - information every athlete should know, how to handle recruiting, etc.
The College Board - search colleges, sign up for your SAT test, see college entrance requirements