best way to enhance color is to have a good diet for the horse. If your horse has a good diet and is eating all the right stuff it will naturally look good and shiny. Dyes are not a permanent solution, and while it may be fun to experiment, should never be substituted for a good diet.
As far as color, if you're just experimenting just try the one you want. Red will make him either lighter or darker, depending on the tone. Personally, i like your horses color as is, especially his light color. However the decision is up to you! Have fun, and if you do decide to color, post some pics!