To keep your jewellery pieces looking lovely, I recommend cleaning your pieces with a jewellery polishing cloth. With plated items, polish gently so not to damage the plating. You can use warm water and a mild dish detergent to clean your jewellery, ensure you thouroughly dry it afterwards.
Take particular care when cleaning pieces with gemstones, use a soft toothbrush to clean round them. I wouldnt recommend the dip style cleaners as these are not suitable for gemstones, pearls etc.
Copper pieces - Copper naturally oxidises over time and changes colour (patina). Skin chemistry can speed up this process and as each persons skin chemistry is different, timings of this change can vary. This oxidisation can, for some people, leave a greenish colour on the skin, to minimise this please clean your pieces regularly.