I usually try and match my colors pretty close. Its rarely a perfect match though. The blue in the skirt might be different from the blue in the trailer, but that's never mattered before from my own experience. Just do your best. Critters in the wild have all kinds of different shades and imperfections so if you're off, it shouldn't be a big deal. And remember, just because it doesn't look good to you doesn't mean it won't look good to the fish. I can't remember the last time I saw a crawdad with shiny blue flecks in its pincers.
Other times though, I will put a slightly different colored craw on my jig. For instance, if I have a skirt that is primarily brown, but has some green strands/highlights in it, I may put a green craw on the jig. It still "matches." Its just not identical. This has also produced fish for me in the past as well.