There are many different things to consider when caring for your 925 sterling silver jewelry but lets start with the numbers. Sterling is an alloy of silver containing 92.5% by weight of pure silver and 7.5% by weight of other metals, usually copper. This percentage of fine silver is why you will see sterling silver referred to as '925 silver' or hallmarked with a 925 stamp. 
How to Prevent Tarnish from Developing
Substances such as lotions, cosmetics, hair spray, other hair products and perfumes will cause corrosion and accelerate tarnishing. To prevent tarnish from developing, always put your silver on last when applying products. Direct sunlight also causes tarnish, so be sure to take it off before swimming or sunbathing. To prevent tarnish from developing, always put your silver on last when getting dressed up.
How to Store Your Sterling Silver
As mentioned, preventive care is always easier than aftercare because you'll save a lot of time not having to rigorously clean your jewelry. The most common way silver gets tarnished is by exposure to air. To prevent sulfur and humidity from damaging your assets, store your silver in an airtight, fabric lined box when you are not wearing it. An alternative is small zip-lock baggies. When storing, also keep it out of direct sunlight and don't put it in contact with items that contain sulfur. This includes wool, latex, rubber, mustard, onion, and eggs. It may sound a little... off, but no sulfur=safe jewelry.
How to Polish Tarnished Silver
If you silver gets tarnished you can polish it with a simple warm water and soap solution. After polishing with a cloth, you want to dry it immediately. If this doesn't work then you'll need a more serious solution. A home remedy is taking an aluminum surface that can be filled with liquid, and pouring enough hot water to cover your jewelry into it. Mix in 1 tbsp of salt and 1 tbsp of baking soda. After dissolving, place your jewelry into the solution touching the aluminum and let it sit for 5 minutes. Afterwards rinse and rub dry, then polish remaining spots with a cloth. An alternative is getting a professional cleaner.
To keep your silver fresh, follow this care guide and shop Tranquil for extravagant silver pieces.