If you stick one on the bottom of your nuts, it lifts them up just enough to get them started first try. 
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The problem with the battery post and square nut is; gravity holds the nut in the bottom of the post channel. If you have one or two cables or extra wires to thread on top the positive post (I think I have 5 or 6 because I'm too stupid to wire up a fuse block) then the screw does not reach down to the square nut in the bottom.
I've used foam earplugs, a small piece of vacuum hose, or anything small and spongy that's not metallic.
And use dielectric grease to fight corrosion.
Another thing I like to do is write the month/year on the top of the battery with bold magic marker so any time you're in there you get immediate notice of it's age. I keep a pretty detailed journal for each vehicle and bike with dates, bike mileage, and things done (oil/filter, fluids, tires, batteries) but I don't have to hunt it up and try to find my last battery entry, if it's just written on the battery itself.