I've personally had the most success with yellow and a black pupil but in all honesty I doubt it really makes much of a difference. I've messed around with a lot of colors and haven't yet noticed a combination that really stands out. If it makes it any easier, I just buy plain lead dumbell/eyes or copper beads and then use fingernail polish to paint them to whatever color eye combination I desire. It's very inexpensive and holds up fairly well unless your streamers get smacked into bridges fairly often like mine do.