Granite is one of the strongest materials on earth.
Wipe wet spills immediately, acidic liquids like: citrus juice, alcohol, vinegar or soda. Always use costars.
Do not cut on countertop, always use a cutting board. Cutting on granite will dull knives and will scratch the granite.
Use placemats if hot or metal dishes are placed on them.
Do not use harsh abrasive or chemical cleansers or acidic cleansers on your granite.
Use soft cloth to wipe surfaces instead of abrasive pads (steel wool) that might scratch the granite.
All stones are sealed with a protective sealant. It might be a good idea to reseal your countertop once a year to look it fresh especially if you have light color granite.