All metals will develop a natural patina (tarnish due to the process of oxidation) over time. Some people love the look, while others...not so much.
Everyday tips on caring for jewelry:
- Keep your jewelry dry - take off when showering, swimming, working out, etc.
- Store in a dry place, such as a ziploc bag or a jewelry box with a piece of chalk in it (the chalk helps to soak up moisture in the box!)
- Avoid putting lotions, perfumes, etc. directly on your jewelry
- Avoid harsh cleaning chemicals
After each wear, you can clean your jewelry gently with some water and a soft cloth in order to remove skin oils, dust, and make-up, it will really help prevent the forming of tarnish on your jewelry.
You can also you a polishing cloth on copper, brass, silver and goldfill.
Some people clean their jewelry religiously, others never...it's truly up you!
Check out this article from Harper's Bazaar for some more tips: