As one of the 1 in 11 colorblind guys, roaming the earth, I have challenges with red anything. I have tried many different colors, painted on the front sight. My current favorite: white base coat, 2 coats orange, and a blue, micro fine Sharpie line up the middle, on top of the orange. The fine line appears as a dot, on an orange background, on the front sight, allowing me a very precise sight picture.
I also find it helpful to black out the rear sight, on a stainless gun.