Shenloanne: At the risk of not really helping and maybe even confusing you, I am going to give you a couple links.
The short answer is that it doesn't matter what colors you use when you do
OSL (red, blue, yellow, etc.) What matters most is understanding the concept and how the radiant light is applied on the surrounding surfaces. While lots of folks may use blues, it might actually be easier to use what we think are the harder colors like reds and yellows due to their natural transparency properties.
I have a three part series on
OSL and "how" to go about doing it. The actual hues (colors) you use don't really matter in the end. It becomes a matter of getting the right value (lightness or darkness of the hue (color) you want more than anything else.
The link jumps to 5 posts that cover a number of aspects of
OSL and some of the common pitfalls when attempting it.
I hope this helps get you started. Once you understand the concept, the colors you use become irrelevant.
http://fromthewarp.blogspot.com/search/label/OSL