Read
Communicative Competence by Sandra Savignon. She is a professor of French, and touts the principle of communicative competence over standard classroom technique. Orignally written in 1979 and 1980 (i knew her at that time), it has been reissued in a second edition dated 1997.
Communicative Competence: Theory and Classroom Practice Texts and Contexts in Second Language Learning is probably readily available from a university library system without needing to purchase.
If you go to the linked page, and click on the author's name, you will be taken to a page listing her publications--she has many intersting books on second language learning.
Miss Savignon's point is that immersion is the best method, and learning to function in the milieu of a language has far more value than traditional classroom practice. In the original edition, she quotes Margaret Mead, who said that although she did not learn the languages of the Pacific Islands in the formal grammatical sense, the locals always said she spoke the language better than her linguistic colleagues, because she asked about someone's pig, or how grandma was feeling today (something to that effect). I recommend immersion, and i recommend Spanish. I agree with those here who suggest that you'll pick up the Portugee if you get a good grip on Spanish.