I use lip balm. I put a little square of static cling plastic on top of the upper bout, put on a blob of Carmex and spread it around, and then dap my nails in it before playing. I learned this from the wonderful young Czech guitarist Petra Polackova.
2013 German Vasquez Rubio Concert Special "Bernardi"; German spruce/Brazilian rosewood
2014 Garrett (Gary) Lee spruce/cedar double top; Brazilian rosewood