Any sort of version control is a good idea.
I would recommend using GitHub (Or your own/another git server) as it should make it easier to merge engine changes for later QA builds from Epic.
In reality, use whatever Source control solution you feel most comfortable with.
(Note: GitHub repositories are public unless you pay a monthly fee. Bear that in mind if you plan on selling your project.)
Some solutions you can setup yourself:
Git: http://git-scm.com/
SVN: http://subversion.apache.org/
Perforce: http://www.perforce.com/
Happy coding! 