Battery terminal corrosion prevention

I use the protectorant impregnated washers, and the spray......this is after cleaning the posts and wire terminals of course. If the corrosion is bad, I use baking soda and water to clean them. For your overspray problem, hold the terminal in your hand with a paper towel behind it to keep the spray from going everywhere. If you can't pull the terminal away far enough to do it, put the spray on a small paint brush and apply it that way.