Dear dawn,
Hi!
21 or 22g are useful for earring wires and headpins, most small stones and pearls are drilled to take 22g or smaller though many of the ones under 3mm will require 24 or 26g. I use mainly 20g to 24g and I like to keep at least 1/2 oz of each at any time. I use half hard for the smaller wires, if you want to do coiling you way wish to use dead soft for the wrapping as the wrapping will stiffen the wire.
If you want to try making your own clasps like Elly has recently, you may want some 18 or 20g, what I did was buy small amounts different sizes with each order and when I new which ones I used most often I ordered more of those.
Have a look at you current work, ask yourself am I making lots of small, delicate pieces or do I like large, chunky beads? The bigger and heavier your beads are on average, the bigger the wire you need.Hope this helps a bit,
Love, Jan[:)]