Let's be honest, if you've been avoiding learning it for years, it's hard to see how a flash card system is going to turn the entire thing around. It still takes a lot of discipline and effort to stick to it.

If you already live there, forget flash cards, take a basic in-person course then just pick up a newspaper, turn on the TV, talk to that gas station employee in your broken German... Having actual conversations, no matter how broken, is IMHO way more beneficial than any app or course. And yes, I've learnt several languages (including German) this way. There's countless ways, but in the end it pretty much boils down to the willingness to learn it, not an optimal learning method.