I think the way which will not do any badness to your glasses is good. I can tell you an easy one. You just need a bowl of warm water and drops of soap solution.
Firstly, drop the soap solution to the water, and then swirl it with your hand.
Secondly, take off your glasses. Place them to the water and wipe the lenses with you fingers clearly and slightly. By the way, if the lenses are glass, you can scrub them in any direction you like. But if they are made of plastic, you should scrub them in only one direction.
At last, dry the lenses and frame with the glass cloth or a piece of 100 percent cotton cloth.