I claim no responsibility for you trying any of these.

First I try canned air to blow stuff the lens. Lots of times it is just dust that is held to the lens by 'static'.

Secondly if the canned air does not work I tend to use Distilled Water (pure distilled, de-ionized water). Tap water or bottled water contain minerals and other contaminates. Then with newly opened package of Johnson & Johnson sterile surgical cotton and only the pressure on the cotton should be its own weight (using a new cotton ball each time).

Lastly, if it is really dirty I use 99%-97% Isopropyl Alcohol (ask your pharmacist) and a new New plastic spray bottle (do not use one that has been used for any other purpose) with Distilled Water (pure distilled, de-ionized water). Rinse the plastic spray bottle with Distilled Water (pure distilled, de-ionized water) vigorously shaking to make sure it is clean in side - repeat at least 3 times. Now your Plastic spray bottle should be ready to use. Fill 1/8 of the bottle with 99% isopropyl alcohol and 3/4 of the bottle with the distilled water (pure distilled, de-ionized water). Screw on the pump spray top immediately to avoid dust or other particulate material from entering the solution. Now home made solution is ready to go... Do not refrigerate. Again I use the package of Johnson & Johnson sterile surgical cotton and only the pressure on the cotton should be its own weight (using a new cotton ball each time) to clean the lens.

I start at the perimeter of the lens and spiral around toward the center. I replace the sterile surgical cotton ball with each and every time. I am sure it does damage the lens on some molecular level but hopefully I will never notice the damage within the lenses life time.

Most 'paper' type lens cleaners are really abrasive and lead me to believe they will have a greater chance of scratching your lens over time.

I use lens filter to avoid my time consuming lens cleaning process. Although I still inspect them clean them when needed - usually a yearly cleaning is required.