My simple solution is to go to Brownell's web page, search for sight paint and spend $14.95 for 5 colors. Degrease your front sight and use a toothpick (not brush!) to daub a little paint on the front sight's rearward edge. Use an old business card to protect the sides of the sights or remove "spillage". Let dry. Try it. If you don't like it, you can remove it and try another color.
Use one color for the front sight -- white or green say -- and a different color for the rear, like red, so your eye picks up the front sight easier. Personally, I find you don't really need paint on the rear sight if you can see the front one.
BillCA in CA (Unfortunately)