Ah, I see. This is a difficult subject for me, too. I think what helped me the most so far was studying color theory, namely, how different types of colored lights interact with each other and various surfaces. For example, if you shine red light on a green object, it appears black since it does not reflect the red light back, it absorbs it.
A more reliable method, of course, is to find adequate references, or experiment with them yourself. Although I'd imagine it's not that easy to put your hand on differently colored light sources.
