He means your sig colors.
Try to use more than one color for your sig background.
And don't have the stock images contrast so much with the background. It's not smooth at all.
And on a side note: I don't like your border's on your sigs. Tech borders are fugly, IMO. Scanlines just ALL over the sig aren't too creative. You need better, simplier fonts.
My fav. sig is this:
But I don't know how much work is your own. It's one of your best though.