I use a well dilluted soapy water, such as dishwashing detergent, (i.e. Palmolive, Lux, etc..) and a soft cloth to clean it, only after I've wetted it. You don't need much, a teaspoon per gallon of water. Rinse liberally, then dry with soft natural cloths. (Synthetics tend to not absorb water, and also leave very small scratches in the surface.
REMEMBER: You must NEVER use an abrasive like many polishes have in them to polish it. There are a number of them out there, but if you're semi frugal as I am, I never polish it just clean it frequently, also because I've found that most polishes have chemicals in them that leave a tainted odor in side. (You must do both inside and out.) The best insurance of a clean top is to never allow anyone to smoke inside. The smoke adheres to the surface of the panels of the top and takes forever and a day to get out.....