Use air first (a blower, not canned or compressed air). I find that most of what settles on my lenses and filters blows off. Cloths of any sort are reserved for what won't (fingerprints, etc.) or regular cleanings, which I do a few times a year.
Soft and free of lint and chemical contaminants are the things to look for.
Microfiber cloths work well, but being re-usable, they tend to gather dirt and oil from handling. They can be washed, but it has to be done carefully to avoid impregnating them with soap or hardening the fibers, which can happen if dried with heat.
I use Pec*Pad wipes and Eclipse (very pure methanol) cleaning solution, both from Photographic Solutions. The pads meet the three criteria above, are disposable and large enough to clean both ends of a few lenses before running out of unused spots. A pack of 100 pads runs about US$10, and I've been through maybe two and a half packs keeping two SLR bodies, a half-dozen or so lenses and a handful of point-and-shoots clean over the last decade. A two-ounce bottle of Eclipse is about the same price, and I'm barely into my second bottle. The methanol helps break up things that stick to the glass, won't harm coatings, wipes away very easily and evaporates quickly without leaving residue.
One other bit of advice: Camera lenses should be kept clean, but they don't need to be surgically clean. Do your cleanings sparingly, and only when visibly needed. Anything too small to see with the naked eye isn't likely to have an effect on your pictures unless it's attached itself to your sensor.