Jewellery, whether fine or costume, is not really designed to be worn in the shower, pool or sea. Nor is it a good idea to keep it on for housework or gardening. Prolonged exposure to air, especially in humid conditions, will lead to darkening of most metals. Costume jewellery, such as charm bracelets, lightweight maille and bling rings needs to be treated with a certain amount of respect - avoid bashing against hard objects or catching in clothing if possible. If you use perfume, hairspray or sunscreens, it's best to apply these before putting your jewellery on.
The simplest way to avoid tarnish and damage is to store your beautiful things in sealed 'ziploc' type bags. Not the prettiest of solutions, but very effective as they keep out the air that causes metal to oxidise. They will also stop them from bumping together and scratching or damaging metal, stone or glass. Not all glass beads or semi-precious gemstones are entirely colour or lightfast, so it is recommended that you store these in a dark place away from direct sunlight.
Always be gentle! Sterling silver - even items with lampwork beads or stones - can be cleaned with a polishing cloth (I like the Sunshine brand), but as a general rule, the simplest cleaning solution is warm soapy water and a very soft toothbrush. Never use an abrasive cleaner (even toothpaste). Some glass beads (especially the tiniest seed beads) can lose colour when immersed in water.
Copper jewellery will darken to a rich reddish brown very quickly. If you prefer the 'bright new penny' look, just add a tablespoon or two of lemon juice to a cup of water along with a teaspoon of salt and soak the piece for a few minutes. Rinse and dry and it will be as shiny as shiny can be!
Your jewellery may get damaged or broken eventually. I am happy to offer a repair service for any piece costing more than £25 purchased from me. Small repairs are undertaken free of charge other than postage cost, provided they are the result of normal wear and tear and not due to jewellery abuse! If more extensive work is needed, I will provide a quotation before starting.