Immersion does work, but here's a more enjoyable version:
Take 4 years in school, don't learn enough to talk to anyone.
Marry a Latino/a.
Go visit their original country with them.
Feel like an idiot.
Practice with your spouse.
Go back and feel less like an idiot.
This has the advantage of getting a hot spouse, and slightly less likely to be killed before you learn enough.
Funny that, I did exactly that with that post... I probably run about 50% overall on these.
Sometimes I look at what I'm about to post and decide that nobody really needs to see that.
Sometimes I look at the other comments and decide I don't want to interact with the whole thing.