Dust is abrasive, first thing you need to do is remove the dust, its microscopic and you can't see it, but if you drag it over your lens you are going to scratch the coatings, thats why the brush on the lens pen is the first thing you should do to remove any dust or fibres. NEVER use a paper product unless its the lens cleaning papers that you got from the camera store. I then use a little bit of alcohol on a cotton ball and go lightly in circular motions from the middle to the outside, that will move anything the the alcohol removes or dissolves to the outside of the lens. the alcohol will dry really quickly. After that you can polish a little bit with the micro fibre or the cupped end of the lens pen, never press and rub, just light strokes, always circular from the middle to the edge. I also always keep my lens caps closed and put cotton balls under the lens caps to absorb any moisture or dust that might somehow get in.