Things you will need.
-Airbrush
-A model
-A sexy outfit
Things that help, but are not needed
-Flow improver
-Wet pallette
-Sandwich
Okay so you have some models that are base coated for the most part.
What you are going to do is airbrush in light coats with a rough 3:1 mix of thinner and your chosen color. Airpressure is not super important, but running your compressor on a low pressure helps. I use around 8psi I think.
So what you do is you airbrush the glowing object and everything around it that the light from said object would touch. You can angle the air brush as well so the paint lands on the spots light would touch so it makes things a little easier.
So now you have basically what you want. So lets make it better! What I do is mix a darker version of the color and dilute is into a wash with some flow improver added into the mix. Throw that wash on the airbrushed areas and wait for it to dry. Then highlight from the part of the model that would have the most vibrant light and do lighter and lighter layers the further from the source you get.
Wooooo OSL is now complete.
( I photoshopped this picture so that only the glow from the dagger is in color )
Notice how objects that have the color are brighter the closer they are to the subject and then get softer and just fade back off into the grey. Also notice how there is shadows behind the areas the light hits. Seems pretty simple right? Well it is, and its even easier once you get some practice in.
You can do a model from primed to finished with nice OSL like the model on the right in a couple hours this way. The OSL on that model started off with the same green as the Stalkers above. Just to get a idea on how they are going to turn out when finished as well.
Hope this helps, if anyone has questions I will try my best to explain.