I start reading about it, from their website, forums, blogs, etc.
Next thing I usually do is to take a look at stuff made of that tech and mess around to see what it looks like.
Then I pick a book about the subject, set up the basics and start from the very beginning, even if the prologue starts with "programming is..."
At some point I start to connect concepts previously seen in the first step with the chapter I'm in, or even identify elements discovered in the second step.
Works for me.