Actually, some very reputable colleges don’t take SAT and ACT scores. Some examples would include the University of Phoenix, ITT Technical Institute, and Kaplan College.
(On a serious note, CSUs only require the SAT/ACT if you have below a 3.0. Above a 3.0 they are only strongly recommended)
Anyway, I would tell myself to not procrastinate asking for letters of rec, and to seriously consider who I was asking. I’ll forever kick myself for getting one amazing rec and one awful one.
I would also tell myself to buy one of the AP crash courses rather than trying to read the entire Princeton Review book in one night 