When I moved to France, I didn't speak a word of French ("sortie" on the highway was the first I learned when I was moving my stuff).

I took 2 months of a half-day crash course at Grenoble University (not cheap, but very efficient), and after that I could get along. Six month later I was able to fight back a supplier on the phone.
At this time (25 years ago), people did frown at you if you didn't at least try French first. This has changed considerably since.

And as Chris said, immersion is the key. Also important - don't be afraid of making mistakes. 25 years later, my family is still sometimes laughing at me... but then I'd switch to German and have a laugh at them.