Testing branch and versioning.
I work on develop. I branch from there to add new features. New features, when stable are merged into develop, and from there into master to form a new version.
I take the general rules from here.
(on branch development)
$ git merge master
(resolve any merge conflicts if there are any)
$ git checkout master
(there won't be any conflicts now)
$ git merge --no-ff develop
(remove the branch if you don't want to keep it)
$ git branch -d contact-form
(push your changes to remote)
$ git push origin master
I also do this between features and develop.