I speak 2 languages natively, but have recently studied a third (Spanish) and speak it at a beginner, but passable level. I really recommend the Pimsleur method for learning languages. It's a set of audio lessons, where the basic principle makes a lot of sense: learning the same way you learned your native language. Simply by hearing things said, over and over, and taking part in mock conversations. There is exactly zero time spent on teaching you rules, it's all taught by actual talking.
On the one hand, there's been research showing that people who move to a foreign country and explicitly learn the grammer learn the language faster than those who only learn naturally.
On the other hand, I think both methods can get at the same aim: massive memorization of both new material and the natural use of patterns.
When we learn a language "from birth" (of course it is more of a 6-year full-time immersion program, which isn't all that amazing in itself than something that happens the day you're born) do we learn the patterns without realizing, or do we literally have to memorize each new adjective ending for nouns in different cases and genders (eg, in German)?
I assume our brains pick up on the patterns, hence why kids make cute mistakes like "I'm the goodest". BUT, as an adult, why not just learn the pattern explicitly AND listen to and participate in lots of conversations AND memorize a lot?
They ALL help. Do as much as you can as often as you can and your learn will spiral out of control awesome ;-)
EDIT: I'm also not sure whether only-memorization to learn patterns works or not. When people say they're "conversational" in 3 months, how much can they achieve in 3 more months? It's a question of whether memorization or whatever process they're using is exponentially scaling. I think that most grammer patterns can be made clear with 3-50 examples, so in the end that doesn't seem that difficult. But I've only had experience memorizing grammer first, with the help of hundreds of examples at the same time, and then producing hundreds of examples myself to become fluid.
Link to wiki for more info: http://en.wikipedia.org/wiki/Pimsleur_method