Sterling silver is 92.5% silver and 7.5% other metals (usually copper), which means that it will tarnish over time. It is easiest to prevent tarnish rather than spend all your time laboriously polishing your silver jewelry.
1. Wearing your silver jewelry everyday will prevent tarnish, as the oils from your skin will naturally polish the silver.
2. It is best to store sterling silver jewelry in a cool, dry place (not the bathroom) and preferably in a plastic bag with an anti tarnish strip. I like to use these anti tarnish plastic bags for extra protection. Another option is to use anti tarnish pouches that not only prevent oxidation, but protect the jewelry when traveling.
3. Many household chemicals, including chlorinated water, lotions, perfumes and hairspray, can cause corrosion or increase tarnish. It is a good idea to remove silver jewelry when doing household chores, swimming or cooking and put your jewelry on last when getting ready in the morning.
4. Some of the worst cases of tarnished jewelry I have personally seen are when silver jewelry is stored on or in a decorative metal display. I try to store mine in a jewelry box or in plastic or anti tarnish bags.
5. If your silver jewelry does oxidize, I prefer to use a polishing cloth instead of the commercially available silver cleaners. Commercial cleaners work well in removing surface tarnish, however they can also be unnecessarily harsh and eliminate any purposeful patina intended to create contrast. Also, brittle or soft stones (such as, turquoise, coral, amber, opals…) and pearls can be harmed in a commercial cleaning solution. I most often use either a buffing and polishing cloth or a Goddard's polishing cloth to remove any tarnish and shine up my silver jewelry.
6. You can also make your own gentle jewelry cleaning solution with a little warm water and natural dish soap. I use a soft toothbrush to get into all the little crevices and clean off any extra grime. Be extra careful with jewelry containing brittle and soft stones or pearls. Dry your jewelry with a lint-free flannel, microfiber, or other soft nonabrasive cloth and avoid using paper towels or tissues that could scratch the soft surface of the silver.
7. If your jewelry is particularly tarnished or fragile, it is always a good idea to take it to a professional to clean!
Hope these tips help!