Taking care of your handmade jewelry is quite easy.
Jewelry made of pure copper or silver will oxidize over time. Most of the pure copper jewelry I make have had a patina applied and then parts polished to bring out the shine. These too will darken over time but only need a quick polish to bring them back. All it takes is a quick scrub with some superfine steel wool if it has turned completely black or likely just a polish with a cloth to bring back the shine. I recommend the Sunshine Cloth* for polishing. It works the best in my opinion, but most polishing cloths will work.
Store your pendants away from the elements and never wear them in the shower or swimming. Also avoid leaving them in the sun or wearing to the beach as the sun may affect the stone. Apply an lotions or creams before jewelry to protect the metal and focal stones or beads. If dirt gets in the jewelry, they can be cleaned with mild dish soap and warm water. Make sure to dry thoroughly.
*I do not get any benefit from recommended Sunshine Cloths. I just like them!