I read just enough about it that I can get a "Hello, World" program written and running. I then try a few things to modify that program to learn more about the language. In particular, I'll often try breaking it in several different ways. If I know what I broke, then I can learn how to interpret error messages.
Once I've done that, it's time to start on a small project. I just start coding and looking up what I need to know. I know in advance that my code will be bad. In fact, the more often I encounter some piece of documentation that leads me to say, "Oh, I should have done it that way", the more I learn.