Git, used along with Github, is a great way to manage the work of writing code. It allows you to collaborate easily on even very large-scale projects, and provides a great place to quickly host code for sharing it with others. If you're going to write significant amounts of code, I highly recommend using it.
Below is a list of commented Git commands in rough order of probable workflow. I use this as a quick reference for using Git. If you happen to want to add comments or questions, I'm making this blog entry into a Github Gist. You can view it here.
git init #start a repo
git add mynewfile.py #track a file
git rm --cached myoldfile.py #untrack a file
git commit -m 'my commit message' #commit changes with a note
git push -u origin master # push to the 'master' branch on the 'origin' remote
git branch mynewbranch #create a new branch