I just did the Testors gloss red on all my front sights. Haven't gotten to the range yet, but just from practicing it really makes it a LOT easier to pick up the front sight. Can be hard to do it right so you don't get red inside your white dot. I painted them with Testors white first as a base to make the red a little brighter. I also used the white to touch up the white ring around my Trijicon night sites (the white part always seemed too dull even when new).
I got a REALLY fine brush and used a magnifying glass, even then it was a little tricky (especially doing around the night sites).
Not sure how durable it will be, and haven't gotten to range yet, but overally I think it really is an excellent thing to do in terms of quickly aquiring the front site.
I decided against orange since a lot of the time at the range I get targets with an orange bullseye. For practical shooting, orange may stand out even more.
Yellow would probably be a good option for visability, but was concerned there wouldn't be enough contrast with the white dot. Red seems to work.