I used to study languages (French, German, Spanish and Italian mainly and bits of others) and still find it really hard speaking in front of a native speaker as I get all embarrassed (though alcohol helps a lot!).
I found that the best way was to be around native speakers and listen - often a different "kind" of language than that you are taught and you can pick up a more colloquial, chatty way of speaking rather than the rigid dictionary version. I went to work in France for a couple of weeks and it made a huge difference to my French.
I find that email/messaging is good as you can think about things and look things up and learn more than copping out if you aren't sure how to say something. Listening to TV, radio and music is also good or watching French films with subtitles, there are loads out there, books too, even children's books to start off. Songs are quite good as it can be easier to remember lyrics and what they mean.
Once you pick more up it's much easier to think in languages and just chat away to yourself. I'm rusty now but used to be able to switch between them easily, used to get tested such as being asked a question in one language to answer in another, it's amazing what you can teach yourself to do when you try though I've always had a fascination for languages.