With both granite countertops and floors, the most important aspect of caring for granite is to reseal it every six months to one year with an oil-and-water- or wax-based granite sealant. Sealing the granite keeps it from absorbing liquids and grease that would otherwise lead to staining.
Sealing the granite also helps to keep it looking its best because without the sealant, it would quickly begin to dull. This is especially important for granite floors because foot traffic can quickly scuff and dull even the hardest stone. In addition to regular sealing, it is important to regularly clean and polish the granite using a soft cloth or mop and simple soap and water.
Make sure not to use anything even remotely abrasive for cleaning because this can scratch the surface. It is also important not to use any cleaning products that contain ammonia, bleach or even weak acid, as these can both remove the sealant and also stain the granite or cause its color to fade. For those who are worried about damaging the granite, there are many commercial cleaning products that are designed specifically for use on granite; although, dish soap cleans the surfaces just as well in most cases.