Copper is known for its natural red beauty, and wellness qualities in comparison to its sister metals: gold, and silver. But, it also has a bad rep for oxidation. Copper, like silver, will darken with patina over time, which can add a great look to the piece. I did offer a lacquer, but found it caused faster oxidation, so I do not often apply it on the face of the jewelry. It also peels off of vitreous enamel, which lends me zero benefits on those pieces. Instead, I wax freshly hammered raw copper with a microcrystalline wax called Renaissance Wax to help stave the natural process, but like all things, it wears off over time.
For those that wish to maintain a bright and shiny piece of jewelry, can be polished regularly using a cleaning cloth (I recommend Sunshine Cloth, which I have with me at shows, but can be purchased easily online), and stored properly in a jewelry box with anti-tarnish paper when not being worn. Patina can be removed with mild acids found in household items, including ketchup, and soy sauce.
Do not wear copper in the shower, pool, or out in the rain if you can help it. If your jewelry does get wet, dry it carefully, and let it fully dry before glazing the backside of the piece with clear nail polish to add a new protective layer.