Hi Steve, thanks for your interest.
My advice to paint a good tartan is to keep the colours as close to each other as you can.....that is dark blue, blue green and green. Do you have Shep Paine's and Bill Horan's books I mentioned in one of my posts? That is the greatest reference you can get. Also Danilo Cartacci's book is very useful as well, as I said in my same post. Also you need to CORRECT a lot when you paint the narrow stripes. At the end when you are satisfied with what you've done, you can apply a very thinned wash of Blue Black Oils. Other then this I really don't know what to tell you except a BIG GOOD LUCK
Regards,
Ray.