Today I had to resolve a git merge conflict with vimdiff and it took me quite a while to find the right commands for this task. Fortunately, I discovered this post which you should read, if you want to get started with vimdiff and git. The most basic command to get a merge conflict done with vimdiff are:

crtl + w, {h,j,k,l} to move from one window to another

diffg (short for diffget) to copy stuff from the {REMOTE, BASE, LOCAL} pane to the active pane.

:diffg RE  " get from REMOTE
:diffg BA  " get from BASE
:diffg LO  " get from LOCAL

]c move to the next conflict

[c move to the previous conflict

:wqa to save and close all open panes in vim

Additionally, the following options are quiet useful:

git config merge.tool vimdiff
git config merge.conflictstyle diff3
git config mergetool.prompt false