Whoa, way to open a question. Everyone does them a little different. My first reccomendation (This is for your Black Templar army, right?) is to look at soem figs in the gallery, find the look you want and PM the person.
My light skinned guys vary on the mood I\'m in, and an army is a great way to experiment a little on each guy. My quick way that I do my Dwarfs...
Base Coat foundation Tallarn flesh
Wash of Citadel Purple wash (Just started this, and I love it)
Paint Tallarn flesh again leaving the purple in the recesses
Highlight with whatever fleshy tone is nearest and lightest. A little variation I find makes the army look a little less \"cookie cutter\" but using the same first two steps often makes the army keep its cohesive look.