git remote add <name> <url.git>
This adds the forked repo as a remote. You don't need this if you have merge privileges.
You can then fetch
and checkout
the branch of your choice
git fetch <name or remote>
git checkout <branch_name> # allow tab completion to help you here.
Often while reviewing a PR from a fork of the orignal repo, it might become beneficial to push up your suggestions into the branch used for the PR. While this is simple if the PR branch lives on the same repo, it can become quite confusing when this branch is from a fork of the origin repo. The step below can be used to push up your changes to the PR branch on forked repo
git push https://github.com/username/forked-repo.git <your-local-branch-name>:<pr-branch-name>