The first thing to note about sterling silver is that sterling silver tarnishes and it is completely normal! It is the nature of this precious metal. Tarnishing (or oxidation) occurs when it is exposed to air and moisture. Avoid storing your jewelry on your dresser or on the bathroom counter as these will expose your sterling silver to moisture in the air. When not wearing your jewelry, store it in an air-tight bag or jewelry box. The best and easiest way to avoid your sterling silver from tarnishing is to wear it! The natural oils in your skin prevent the oxidation process! If you do happen to see that your sterling silver is looking dull, use a jewelry cloth to gently buff the surface. Gentle rubbing will restore it's original shine. Sterling silver liquid cleaners can be used but be sure to rinse the jewelry very well after using the solution as the chemicals can be very harsh.
Avoid contact with or spraying with chemicals and perfumes! Spray perfume before putting on your jewelry. This is especially important for hand-stamped jewelry where the letters have been blackened. Spraying perfume on the blackened surface can cause the blackening agent to shift on the pendant.