I suggest you head on over to GW2 and see how to properly do it. Anything less than the GW2 implementation, and I am afraid you will all look somewhat clueless and incompetent. It really is very nice, flexible, and powerful.
Ers, GW2 has over 400 dye colors. Just about every shade and hue imaginable. Of course, you had to get them. That being said, the actual system is 1st rate. Dyes shared at the account level. Have their own inventory slots. No cost to actually use them. Armor pieces each had 1 to 3 areas that take dye.