Wouldn't you like to know!
If you don't, well, you should.
I mean it.
Nothing. (At least, not now)
Coming soon to a theatre near you
Use the branch master for quick bufixes and such. Create a branch with a very descriptive name for developing new features, such as "orefix" for fixing ore generation. Merge your branch into master when you finish the feature, not before. If you do it randomly, just look at the network graph for June to see why that's a really bad idea.
Commit at the end of every work session, so if you break something, you can go back to it and idiots don't do commits on your branch and overwrite your changes.
Just don't be stupid in general. I don't like stupid people.