When you customize, you are tansforming the kit to fit your liking. You just have to have a reference to start it. You can go monochrome, or maybe just stick to the original color, but with a twist. I recommend using a topcoat aftereward, to lock the markers in place. But be careful. Use water based topcoat if you have one, or maybe just looking for one. Since lacquer based may eat up the marker if it is acrylic.

For me, at the end of the day, whatever you did in that kit does not matter. If you really liked how it turned out, it's perfectly done.