Paul as to how to pick languages up.
I picked German from HS classes which got me open to languages from sophomore to senior year (3 total), and I learned Spanish from, people I didn't much like let's say that over the course of 6 months my senior year. French I just adapted Spanish for and taught myself through reading -- and basically the same with the rest of it (Greek, Latin, and older dialects/languages of English and German)
Once you learn your first additive language. . .the how of it becomes part of your brain it seems and the rest is just gravy. As for that first, either schooling or shock-immersion (move somewhere its the only language) is my suggestion. . .Rosetta stone is okay in a way, but it is slow, painful, boring, and teaches you exactly dick about complex grammar and turns of phrase and you know -- the stuff you really need to know. Rosetta stone is in reality just a primer for before you go off and immerse yourself and should never be used any other way -- or with any higher expectations.