A cotton t-shirt works great for that. Seriously, there are different types of lens cleaning cloths and fluids for that. The cloths can be nice and most of the time the fluid isn't even necessary, but you seriously can just use a nice soft cotton cloth. Anything that is clean and non abrasive, which means no paper like tissue or paper towels. Mark, I sold this stuff for longer than I care to admit, both retail and as a manufacturer's rep and shit like that is why people don't want to buy from B&M retailers. When someone tells you stuff like that, I'm inclined to suggest you tell them they just lost a sale and why.