Although I've found that git is much similar in nature and in syntax to hg (which is also a DVCS and one I've used more extensively before), there are still differences and concepts that I need yet to master. So, I've sought to learn git from the beginning.
Searching for git information, I've found this very good git primer from Daniel Miessler:
Of course it is fairly basic (it's a primer, after all).
If you already know other DVCS, you need something a little more in-depth. This one is a very good and detailed git tutorial, from Lars Vogel:
Now you have what is needed to get started with git. But you'll only really learn it for real from use. So, enter github.com, create a repo, clone and have some fun!