I use git add -p to split apart what I intend to eventually fully get into the repo. Usually, this means separating whitespace cleanup from meaningful commits. Sometimes I use it to make my commits "distinctly describable" -- instead of a big commit saying (in effect) "I did lots and lots of stuff generally to do with BigTask", I am able to describe various steps of that work, e.g. "Refactored models.", "Added supporting .js file for foo mechanism.", "Migration for bar process.", "Controller method and view for baz form."

Generally, I reserve the "make sure it works" step for just before _pushing_ (i.e. making public), rather than just before committing.

I always use either `git commit -av` or `git add -p`, so I can preview what I'm about to do. I never use the freewheeling `git commit -m`.