Git has many tools that you don't normally encounter in day-to-day use.

One very powerful one I've started using recently is the "patch" flag.

Say you're working on a branch, and you discover you need something you've already implemented on a different branch. Not the whole change, just a tiny bit (in case you want the whole change, git cherry-pick or git merge are more appropriate).

Instead of manual switching and code-copying, you can use git checkout --patch (or git checkout -p for short).

It works like this:
I'm on branch featureA and want to copy things from branch featureB.

I execute:

$ git checkout -p featureB

(If you know which particular file or directory you want to patch, you can also add that as the last argument, like git checkout -p featureB src/my_page.tsx)

I now get walked to all parts of the change (called hunks) and get asked if I want to apply them or not:

Very convenient!