I think one of the biggest things I have trouble with as an artist is knowing how to handle coloring involving multiple, complicated light sources. Of course, I know how basic light works and how light and shadows fall on objects, but when it gets complicated, I'm not sure how to handle it. Does anyone know of any basic tips or resource guides for this sort of thing (besides the usual "look for reference images with the same lighting"? Any help would be appreciated!

Do you mean lighting within the picture, or when you're hand drawing it and using a light to help you see?
Either way, try doodling. I used to practice lighting angles quite often, such as the sun at different places in the sky and having a stick figure (or what have you) as a shadow guide. Mess around for awhile.

Yeah, in the drawing itself. (Sorry, I'm not very good at explaining things. >_< )

The best tip is to stop thinking of it as complicated and just GO like you normally would.

Seperate your two light sources onto seperate layers. Say, you have two light sources. I seperate these light sources into seperate layers and draw the effects of them uninfluenced by the other right onto my sketch before continuing to paint. I worry about the light before the details.

Here's a quicky tutorial.

Tutorial!

But yeah, basically... I do a sketch, then I sketch in the multiple light sources independant of each other. Then I have this sketch, sort of like you see in the end result, to reference for where I'm putting the light as I build in the details of the main picture. To handle it, I just draw both light and shadow sets seperately, it's less overwhelming.

Also, linear dodge layers. Especially if you're working to quickly put down colored light, hair glow, etc, linear dodge is definately the best layer for the job.