Jewelry Use
New strict lead standards due to be in place Feb 10, 2009 prohibit the sale of children's products without 3rd party lead testing on items meant for children under the age of 12. This means children's products from very small manufacturing operations or handmade items may become hard to find or nearly completely unavailable due to the costs involved in testing.
I've always made my jewelry with great care and durability, and will continue to make petite sizes with the same care I always have, though not intended for people under the age of 12. Petite sized jewelry is not and never has been intended for use by children under the age of three, due to the risk of choking hazard.
I also recommend not wearing jewelry in situations that may cause it to become tangled, such as sports or other rigorous activity, which may result in breakage or injury to the wearer. Long dangling earrings, necklaces, and hair sticks are the most likely to pose these types of risks, however wearers should be cautious with any jewelry in these types of situations.
Much of my jewelry is made using glass beads and as such, may have a tendency to break or crack, and though there shouldn't be any problems with breakage with normal use, they should be inspected by the wearer regularly to ensure damage such as fractures or chips in the glass haven't occurred.
Jewelry Storage
Oxidation and tarnishing of your jewelry will still take place regardless of how it's stored if your wear them, but you can lengthen time between cleanings by storing your jewelry in air-tight containers such as Tupperware-type or plastic zipper bags, keeping the metal of the jewelry out of contact with the air.
Cleaning Your Jewelry -
There's a variety of cleaning products available on the market used for cleaning jewelry that work great for handmade jewelry containing metals. I personally use polishing cloths for silver and silver-plated jewelry, and probably the easiest brand to find is the "Connoisseurs Jewelry Wipes" available at Walmart stores. These work well and are disposable. For copper jewelry, a lemon juice dip is quick and easy. Neither of these methods will damage pearls or gemstones on your jewelry.
I don't recommend the use of tarnex on jewelry, as when it's used, it actually leaves microscopic pits in the metal's finish, making it prone to catching body oils and tarnish faster. Tarnex is also known to strip the surface off from pearls and several types of polished gemstones, along with ruining the finish on enameled or painted beads.
Helpful link: Cleaning copper jewelry and other copper items.