|20 gauge (0.8mm) and 26 gauge (0.4mm) wire|
Gold plated, sterling silver, silver plated, copper, coloured - the list of the types of wire available is long!
Different thickness of wire is good for different things.
A 20 gauge wire (0.8mm diameter) is a thicker wire and is good for making findings, spirals, and ornamental designs.
The higher the gauge number the thinner the wire becomes.
A 26 gauge wire (0.4mm diameter) is a thinner wire and good for twisting and tiara making.
I suggest these two gauges as a starting point.
Wire is sold in 'spools'. What a great word 'spool'!
Follow this link to see the different gauges available at Beads Unlimited: