The Complete catalog of Dye Combinations

Though most combos use only two different dyes, remember that they offer a nice basis that can still be slightly changed by the use of additional dyes (up to 4). use these combos as a solid basis, but do not hesitate to play with the colors a bit.

here are two practical links:

http://www.guildwarsguru.com/forum/post-update-dye-guide-t10100290.html?p=2409044#post2409044

http://www.guildwarsguru.com/forum/dye-charts-and-dyed-armors-t3047282.html?t=3047282

Good luck...