You probably already know these bits & bobs, but I wanted to share:

  [diff]
    external = difft

Use the fantastic difftastic instead of git's diff. https://difftastic.wilfred.me.uk/

  [alias]
    fza = "!git ls-files -m -o --exclude-standard | fzf -m --print0 | xargs -0 git add"
    gone = "!f() { git fetch --all --prune; git branch -vv | awk '/: gone]/{print $1}' | xargs git branch -D; }; f"
    root = rev-parse --show-toplevel

Those are the most used aliases in my gitconfig.

"git fza" shows a list of modified/new files in an fzf window, and you can select each file with tab plus arrow keys. When you hit enter, those files are fed into "git add". Needs fzf: https://github.com/junegunn/fzf

"git gone" removes local branches that don't exist on the remote.

"git root" prints out the root of the repo. You can alias it to "cd $(git root)", and zip back to the repo root from a deep directory structure. This one is less useful now for me since I started using zoxide to jump around. https://github.com/ajeetdsouza/zoxide