I used to paint the front sight flouresent red, and the rear yellow. Now days I prefer the white dot type. On my S&W's, I remove the red front, put in a black insert, and drill a shallow oval-shaped hole, which I fill with gloss white paint. When sighting, the oval-shaped white insert looks like a round dot. I sometimes put white dots on either side of the rear notch, so I have a true 3-dot system.
On my Python's, I replace the red ramped front with a Colt patridge under cut front. I file the under cut to a slight forward angle, drill and fill with white paint. Gun Parts and Brownells, used to sell 2-dot rear sight blades for Colt, which I have on mine.