If you are good and can afford it, go to one of the few reputable schools that specialize in traditional graphic design. Pratt, RISD, Art Center, RIT, etc...
If you are talented and motivated, you'll learn a lot at any of those schools, but you'll also pay a ton of tuition. However, I'd rather come out of a top school with $80K in debt than a state school or diploma mill school with $20K debt. The former will give you better earning potential because you'll learn more and have a better portfolio.
If you can't afford to pay or don't want to have to have a huge educational debt, then look at going to a 4 year college (that has a good design program). That's the route I took. I did my general ed at a community college and then transferred in as a junior. Once I passed the stringent portfolio review and got excepted into the program, the real hard work began. Make sure that the school teaches a strong foundation in process and elements of design. NOT have you do a bunch of software tutorials and then leave you to do stuff on your own. The school I went to doesn't teach the software- for the most part, they expect you to learn that on your own. What I learned is creative development process, design fundamentals, color theory, type... etc. Oh, and also how to stay awake for 2 days straight.
Finally, do some soul searching and decide it you really have a passion for design. It's tough to learn because it encompasses so many disciplines. Prepare to do overnighters if you're not extremely organized and motivated. At my school they piled on the work and were critical of whatever you put out unless it was amazing. And, there were ALWAYS 2 or 3 students who do better work than you, so it can be demoralizing. What kind of "designer" do you want to become? That will tell you what direction you want to go in. If you go to a traditional design school, don't plan on doing a lot of "art" type of stuff. Or, if you are into film/video and photography, you won't use that as much as type, shape, line, dot, space, color.... We had to do large posters with nothing but type and 2 colors to work with.
Hope that helps.