Immersion is the best and easiest way to learn anything. So, short of going to France to live for a while I'd be looking to meet French speakers (check out the Couchsurfing social meets, they should prove fruitful - however, a lot of foreign speakers are keen to speak English). There are a few websites which will translate other websites into a language of choice which could be a good way to do it.
At a very basic level, then I've had some success with Rosetta Stone but you need to be pretty disciplined to make it truly work.