Moving to GitHub?

Since a few people have suggested moving the project to GitHub, I am willing to give it a try. Before doing so however, I’d like to collect some input and feedback. First, how should we set up the project on GitHub? The simplest way would be to move the entire SVN tree (with trunk, sandbox and all branches) to GitHub. I don’t really like the idea, as there’s no need to move the old release branches over to GitHub. Also, some parts of the SVN repository (sandbox) could need some cleanup. The other issue is that I plan to integrate the changes from the 1.3.x branches into the trunk. How can we set up the Git repository, so that this integration can be easily done? And finally, are there any specific things to take care of? Best practices?