I've used it to pick out shirts with suits. I've picked out scarves based on my jackets. You can go monochromatic (shades of all one color) or you can do some cool three-color looks at the... points on the wheel? (sorry, I'm not so versed in the terminology)

We're talking about art here more than science, so there's no breakthrough right answer like in mathematics. My experience is that I'm more savvy and I start to notice the patterns, but my skill level isn't high enough that I can lecture on the topic intelligently. It's like, after doing all this stuff I have intuitions when shopping for clothing and dressing, and I tend to get complimented on what I wear, which didn't happen before I studied.

I hate vague answers like that - I wish I could give you something more concrete. It's not the "oh you just have to figure it out" whimsical idealism, it's that I lack the skill to give a more cohesive and concrete explanation... apologies for that. If you know anyone who is an excellent photographer or painter, and is also good at explaining things analytical, they might be able to provide more answers.