First, you must make sure you're able to run the test suite.
Get this random shunit2 fork in ~/src :
git clone git@github.com:deniscostadsc/shunit2.git
add the resulting directory to your $PATH, and run tests/all.sh.
Tabs are used for indention.
When using commands, prefer long options against short options. I invented the following rule, please follow it:
Short options are for the command line, long options are for scripts.
Also, try adding tests along with your contributions.
Creating your php plugin is as easy as creating a php folder under hooks/php.
You can then create hooks in it. For the moment, only the following are supported
(because I'm lazy)
post-commitpost-checkoutpost-mergepost-rewritepre-pushpre-commit
If you need to add configuration variables git configuration, you should prefix them with the path to your hook, which is obviously unique. This will avoid collisions.