When working with power tools (especially sanders) keep a shallow bowl nearby with a bit of water and a sponge. Power tools generate wood dust and, when it gets on the hands, the fingers lose some grip and can actually become slippery. Not a good thing when you're holding something razor sharp turning at 8000 RPM.
So every so often just pat the top of the sponge with both hands to get them moist and rub them together briskly to dry them. You'll have a lot surer grip on the tool after you do.
FoggyTown