Certain people (formerly) on this board, who shall remain nameless, used to use their tongues. This is certainly not the recommended method how ever.
They're not here any more? Hmm... oh well, the lens licking story lives on in infamy!
Some of us use a "Lens Pen". Here is a link to a mind numbingly boring video that will explain the basic idea of what a "lens pen" is.
I picked one up but have never been particularly impressed with it. Of course, it was an incredibly cheap Chinese knock-off... Pison, I think.
I also keep baby wipes in my bag for cleaning off the LCD screen in the back of the camera. My nose Loves to slime that screen.
I'm going to make my millions inventing a baby wipe attachment that you can wear on your nose while using your camera so that you can save the step of always having to wipe off the nose prints.
Marlton Mom
Good to see that I'm in good company here.

Nose marks are always an issue. I always hold the viewfinder up to my left eye, which makes the problem even worse. I think that originally I did that as I could only really squint my right eye closed. I can do either eye now, but it just feels unnatural after all these years of using my left eye... apparently some people keep both eyes open and use their right in the viewfinder, but that seems
really wacky to me.
Re: t-shirts... I've used mine a few times. Your average t-shirt has been through a bunch of washings and is probably going to be very soft and unlikely to do much damage. The coatings on the glass should be pretty tough; I'm not too worried about those. I definitely have some lenses with some fine scratches in the lens but they are very fine, and just day-to-day dust (on the front element and/or on inside elements) will probably be more of an issue. Besides, as some have said, "lenses are for looking through, not looking at" - you are unlikely to ever notice scratches unless they're pretty severe.
My main microfiber cloth is something called a
Spudz; it's a microfiber cloth that tucks into a stretchy "bag" on a clip. I keep it clipped to the left strap of my camera at all times. Plus, it's 18% gray - good for getting the white balance exact. (I rarely use it but it did help on my last trip getting some shots near a window in Columbia Harbour House, where the light was a strange mix of outside sun and inside artificial lights.) Only $7; well worth tossing into your cart on your next B&H or Adorama purchase.
Disney sells almost the exact same thing in a Mickey-logo bag, but it's a smaller cloth. We keep one of those on the wife's camera.
