I use the shirt I am wearing probably a dozen times a day to quickly un-smear something I have touched and continue to need to look at. But, after doing this, eventually a more thorough cleaning needs to be done to try and get things back to clean.
Assuming that you have some sort of protection on the surface you are cleaning my secret weapon is simply rubbing alcohol and a paper towel. This is especially great at dissolving any grease or oil.
If you have a special protected coating on your glasses or some other specialty electronic device, use this idea with caution! This is such an inexpensive cleaner and works so quickly that it is certainly my favorite. And, the added bonus is that because there is barely any water there won't be streaks or droplets where you had water evaporate from a different cleaner!