This might be a “duh” one, but I used to butter a pan by just picking up the stick of butter and rubbing it around in the pan. Even if I tried to hold it by the wrapper, I’d still get butter all over my hands. Then I saw Isabel do the following:

Put some butter — about half a tablespoon — on a clean paper towel.

Use that to rub the butter all over the pan. You can always add more butter to the paper towel if you run out. Then throw the paper towel away and wonder why you haven’t thought of this before.