Mic there are exceptions to everything, but rubber legs and bi color take gills more consistantly then any other type of fly, IMO.
I tie my spiders in yellow and black. Yellow/black centipede legs on the yellow and chartreuse or white on the black. I tie them on Daiichi 1710 in 10's and 12's.
Tie a strip of foam, about 3/16" wide and half again as long as the hook, at the gap end of the shank, foam pointing away from the hook. take a piece of foam that is square, it will be about 2mm wide, and tie it with long wraps on the bottom of the shank. (you can substitute vernille at this point, but I don't) When you're tying this in stop at the half way point of the shank and pull the first foam piece over and tie it down a that point. tie in a piece of leg so that that a leg on either side points down at a 45 degree angle.
Wrap the thread forward, wrapping the small piece of foam as you go, to a point halfway between the last tie and the eye. Wrap forward to the eye and tie everything down. I make a whip at this point. make a quick long wrap back to the last body wrap and tie in a set of legs. Pull the foam from the eye back to this point and tie it down on top of the legs and the wrap holding them, whip finish it. Cut the excess foam. This doubled back foam will give the fly a head and more flotation.
I'll try to post a picture later.