I am looking for some advice on common practices when doing a programming job for someone else.

So i took a pay-per-hour job from an acquaintance who wanted me to develop a little tool in a web environment. I finished the tool in 16 hours and now its time for me to hand it over. I will probably do more jobs like this for him in the future.

Is it common to add the guy as a collaborator on my git repo, even when there will be code from future projects on there, that will be in-progress and not yet paid for?

Should i develop on another repo/fork and only push 'public' code to a shared repo once my work is finished?

Should i share source code at all, or only share compiled/deployable project folders?

I am not familiar with the common practices in this aspect of the programming business; this was the first programming job i got.

Thank you for all your (future) replies!