1/ Several basic commands will serve you a long way:
git clone
git add
git commit -m
git push
Those are enough to get you started. To be honest, those are still the most frequent commands I use.
2/ understand git and github. You use git to track files locally, and github can host your repos. You can start with the github skill page https://buff.ly/3tO2iaf
gitlab https://buff.ly/3JlGA69 is an alternative to github
3/ software carpentry git workshop is a nice resource to learn git https://buff.ly/3kUhqB74/ An open source game about learning Git! https://buff.ly/2ZPXUrX5/ Learn it for free on Udemy https://buff.ly/3RvTCA96/ The best interactive tutorial for learing git branching https://buff.ly/2tQTJN4
I had a lot of fun playing it.
Oh Shit, Git!?! You know, sometimes it messed up so much locally I just delete my local copy and do a fresh git clone :)
8/ https://buff.ly/2U9C8hC How to use git with R.
9/ git cheatsheet https://buff.ly/3H2PrWa
10/ if you collaborate with others, you need to understand the gihub flow