The master tip: have a detailed written policy on git usage, on what goes into which branch, on git commit message format, and make really, really sure everyone understands it before they start anything. No tips will help if the history is crap.
Is there some kind of git plug in/linter that will check for commit style before accepting a commit? Basically, linting the commit messages.
An example for jquery style commits is https://www.npmjs.com/package/commitplease