To speak a language, to be fluent you need to know quite a lot of vocabulary. I've found a cool website to learn vocabulary, it works like flash cards. It's simple, easy to use and efficient : www.wannano.org. I download 20 words into it on a daily basis (20 * 365 = 7300!! Enough to be fluent!). I can test myself, and see my progress.
How to learn a lot of vocabulary
The bigger challenge will be not forgetting all those obscure words after you learn them.