What makes a good tartan design

[tomcherv]

This may have been posted elsewhere and I've missed it, but, I'm going to ask anyway.

Just for fun, I'm trying to design a tartan. What, in your opinion (and I know there are a bunch out there), makes a well designed and executed tartan.

I've heard/read about having no more than 6 colors, so I'm familiar with that one. I've been playing around with some different ideas, but I'm just not completely happy, yet, with what I've done.

Thanks, everyone.

Tom