I found that using the foreign language regularly was the only way it "stuck". So as you say "immersion".<p>I've married a Finnish woman, and we go through phases where we speak only Finnish at different times. We also agreed she'd never say "no" if I spoke Finnish, so I started with all the obvious things to say "One black coffee, please", etc.
I recommend against most tv and movies because the level is too advanced. You want material that is slightly beyond your level. This is why I recommend reading books. There are graded reading books. Eventually you also need to find a native speaker to practice with. You can do a language exchange or offer something else in return.
The best way if you have the opportunity is to travel to a country where you want to learn the language from. This way gives you lots of advantages because you will feel forced to speak to be able to move around. Practice makes the difference!
Assimil is superb.<p>I have used their system for multiple languages.
Far better than Pimsleur, easier than Linguaphone and pretty cheap.
Small bite sized lessons entirely in the target language, with parallel text.
Quirky humour.
I once heard about a system based around a game: Where Are Your Keys? (<a href="http://www.whereareyourkeys.org/" rel="nofollow">http://www.whereareyourkeys.org/</a>)