A 1:1 mixture of rubbing alcohol and purified water sprayed from a tiny little spray bottle I got for 2 dollars. Darn cheap, and super effective, as well as safe. Only about 1/3 into the little spray bottle after 3 months, and still have almost an entire bottle of rubbing alcohol left that only cost $1.29 for the entire bottle.
Edit: Just realized I already posted before (kind of old thread, i forgot), sorry!