I use a #60 sand paper.... (just kidding)

I use lens cleaning fluid for eye glasses, can of air, and two micro fiber cloths.

First, I blow off dust. Then use a micro fiber cleaning cloth that has been washed along with a lens cleaning fluid commonly used for eye glasses. Then, I use a second micro fiber lens cleaning cloths to gently go over the surfaces. Finally, I use the compressed air again to blow off the lint.

I only do this much cleaning when it's really dirty. Otherwise, a quick blast of air and a light wipe with the above mentioned micro fiber cloth only. I've learned, aggressive cleaning does more damage than dirt ever would.

I do not like paper products because they typically do not absorb moisture and most lens solutions do not evaporate quickly or cleanly. Also, IF grit get caught in it, it scratches badly - more so than cloths would.