For bonus points, use git-buildpackage to build GNU Hello.
To the package dir
cd back to the directory you used to package hello.
Initialize the repository
Mind you, it's a repository in the git sense:
git init
Add the contents of the unpacked source package
git add $( find -type f -not \( -path ./debian/\* -o -path ./.git/\* \) )
Commit that
git commit -m "initial commit"
Add the debian branch
git branch debian
git checkout debian
Add the files and commit
git add $(find debian -type f)
git commit -m"added ./debian"
Build under git control
DIST=precise git-buildpackage