All jewelry: It's best to avoid lotions and prolonged exposure to water, especially salt water. This will speed up oxidation causing your jewelry to tarnish/oxidize more rapidly. High humidity and pollution can also speed oxidation (tarnish). Best practices include removal of your jewelry prior to handwashing or applying any hand cosmetic. The great news is that tarnish is easy to remove with a silver polishing cloth. It can be purchased at almost any major retail store. A quick buff and your jewelry will be back to its brand new shine.
Sea Glass: Sea glass has a rough and frosty finish, if you often wear make-up it can get trapped in this texture. The easiest way to clean is to use warm, soapy water and a tooth brush while gently scrubbing. Remember, sea glass is glass, so avoid hitting it against hard surfaces as, just like glass, it can break.
Sterling Silver: Sterling silver jewelry will oxidize with time creating a tarnish. To avoid this always store your silver jewelry in small plastic jewelry bag when it is not being worn. To clean use a silver polishing cloth. I strongly advise against soaking in silver polishing gel as it might damage the gemstone or sea glass.
Copper and Brass Jewelry: Copper and Brass jewelry will patina with time, this is inevitable as copper/brass oxidizes when exposed to air. Store your jewelry in the plastic bag it was sent in when you’re not wearing it to extend life before tarnish. If you don't like the patina you can use a jewelry polishing cloth to clean. I seal my copper products with Renaissance Wax (should last for several months), but everyone's skin reacts differently and for high wear items (like rings) it can wear off quite quickly.
For this reason, it is important to remember that some people experience oxidation against the skin when wearing copper or brass jewelry (green coloration), if your skin reacts to copper or brass you can add a barrier to the inside of the ring band (like clear nail polish) and reapply as needed.