There is no real answer to this. It is always ok to take more tests! You should probably take the SAT at least early during junior year, and some schools will even require this. Then take it again later junior year or early senior year. Some people will recommend multiple tests so that you become “used to” the SAT, and will probably get better scores. I think this works too. After a while, you just more comfortable with the testing environment, you aren't as nervous and so you do better. On the downside, taking more tests costs more money and also time. If you don't mind putting in 4 more hours to get a higher score, then retaking the SAT is OK. Colleges usually only look at your best performance anyways.

Test planning should begin early, maybe the summer of sophomore year. Enrolling in an SAT prep course is a