Do blot up spills immediately to minimize permanent damage to the stone.

Do clean surfaces using a soft sponge or cloth with soap and water, or an approved stone cleaner.

Do use coasters under all glasses, bottles, and cans.

Do use trivets and hot pads under pots & pans.

Do polish granite frequently. Using a special polish for stone helps protect the surface from fingerprints or water spots by reinforcing the protective sealant. 

Do seal your countertops once every year.

Don’t use generic cleaning products including bleach, glass cleaners, and other degreasers and common household cleaners that contain acids, alkalis.

Don’t use vinegar, ammonia, lemon or orange cleaners.

Don’t use bathroom, tub& tile or grout cleaners.

Don’t sit or stand on your countertops.

Don’t store liquids or toiletries directly on your countertop.

Don’t skip cleaning. Even tiny particles can potentially affect the stone.

Don’t use the stone surface to slice foods. Use a cutting board. 

Natural stone is porous, which requires special care and attention. Sealing is the most important step in preserving its beauty. You should seal your countertops when needed and not based on some arbitrary schedule. Most (but not all) countertops will need sealing upon installation and then resealed once every year depending on the color and porosity of the stone, the quality of the sealer, and proper application.
           
Generally, stone is a durable, lovely surface in any home. However, to keep it looking its best you need to clean and care for it properly. Many household cleaners, including glass, abrasive, and all purpose can dull or damage the stone and leave the porous surface exposed. To properly clean and protect these surfaces you need to use pH- neutral formula specifically made for them or just use mild soap and water.
          
Stone care and maintenance can go a long way if done properly and on time. You just need to follow the basic guidelines and can retain the beauty of your countertops for many years to come.