Requirements to get into a good college?

I'm a sopre in high school right now and I really want to get in to a college like Columbia or Brown. I know that I can do well on the SATS (I took the PSATS and did pretty good on them), but it's the cles that I'm taking that I'm worried about. I'm currently in no AP cles, but am planning on taking a couple my junior year, and around 3 more my senior year. I have a 3.3 GPA, but I'm going to try to bring it up to around 3.8. I don't have any really amazing ECs, and I've been doing random sports here and there not really committing to anything 100%. Do you still think that I have a good chance on making it to a good college if I try hard enough, or is it already too late? Also what sort of requirements (GPA, SAT scores, etc) are needed to get into a college like Columbia?