Clone the repo: `git clone git@github.com:username/repo.git`

By default, you only have the master branch locally:

```
~/repo$ git branch
* master
```

Fetch the target branch: `git fetch origin branch-name`

Check it out: `git checkout origin/branch-name` (note the slash)

Git will tell you that you're in a `detached HEAD` state. That's okay.

Now create a new local branch with the same name: `git checkout -b branch-name`

Tell Git to follow the changes of the remote branch: `git branch -u origin/branch-name`

And you're done.

```
~/repo$ git branch
master
* other-branch
```