The best way to keep your silver from tarnishing is to wear it on the regular! I do recommend removing your jewelry before sleeping and showering, and before swimming in chlorinated water.
To avoid tarnish when storing your silver, place jewelry in small ziplock bags away from other metals - namely base metals which can increase the rate of surface oxidation. You may also consider placing anti-tarnish strips in your jewelry box or along with individual pieces in small baggies.
*When placing necklaces with fine chain into a baggie, be sure to first clasp the necklace and store leave the clasp end and a little bit of the chain hanging out to avoid a tangled mess - trust me, I have learned the hard way!
Cleaning Your Silver Jewelry
I like Sunshine Polishing Cloths for quick and easy silver cleaning and polishing. This versatile polishing cloth may also be used for gold, brass and copper. I recommend cutting one cloth in half - use one piece for silver and gold, and the other piece for copper, brass and the like. Use the cloth to gently remove tarnish and shine up any spots as you wish. Then use warm water and mild soap to clean any residue from the cloth. Dry with a soft cloth.