Instead of using your hands to spread oil or fat in the bottom of a pan or baking tin. I use a cheap sandwich bag. Just stick your hand or fingers (whichever will fit) in the bag, dip in the oil or fat, and spread. As you pull your hand out of the baggie, invert the bag and discard.
When you open a package of butter or margarine, take the wrapper and stick it in a baggie that you keep in the fridge. When you need to grease a pan, pull out of of these wrappers and use it to butter your pan with the leftover butter or margarine on the wrapper. Then just throw it away.