With all the work I have to do for high school these days, I must have a death wish for saying this, but...

I have decided that I'm interested in learning a new foreign language.

I am a native speaker only of English, and am currently in my fourth year of French, so I have been considering the possibilities. Spanish, of course, is an obvious choice, since it is easy to find textbooks, and I could probably get my Spanish-speaking friends to help with pronunciation. (Spanish and French, by the way, are the only languages taught at my school.)
I am also considering studying different languages that I don't have as much exposure to, such as Latin, Greek, German, Italian, Russian, Portuguese, Japanese, Chinese, Hebrew, and Arabic. (Maybe not all at once, though! :-) )

So, the question I have is: how do I go about learning a new language? I have tried several times, with computer programs and books from the library, but I can't seem to get motivated enough to buckle down and use the resources when I finally have them. A big factor, of course, might be that I have so much other school work to do, but I am still interested. Any suggestions?

Sir "J'aime bien le francais, mais je voudrais apprendre les langues du monde" Gawain

(P.S.: How important to students of Latin think is is to learn to speak Latin instead of just reading and wriitng it, since it is no longer spoken much in the modern world?)