Do not try to blow it off with your mouth as saliva and the donut you are eating can get on the lens. Once the loose dust is removed, it won't be there to scratch the surface of the lens while you grind away at the lens with tissue. Using a Q-Tip wetted with a small amount of lens cleaning solution, gently wipe the surface in a circular motion from the outside in towards the centre. If the surface still looks greasy, repeat. Your results will improve with practice, but the care taken will directly determine the life of the lenses.
Mirrors are to be treated with even more care, and less often.
The mirrors in telescopes usually are not subject to the same kind of dirt that eyepieces are, nor are refractor objectives for that matter, so they do not need to be cleaned as often. In the case of mirrors, the contaminants on the surface are usually things like dust and condensation. The dust itself is not that damaging and only interferes with the telescope's performance by slightly reducing the contrast of images by scattering light. But after a while, the dust can react with the water and other pollutants in the condensation to make it stick and perhaps to change benign qualities to something more damaging to the surface of the mirror. Actually, the first method I describe is more like a shower.