Have you tried coming over to my blog. I started it for those of us who wanted to learn to use them. After a year of practicing, I can do a lot better than a year ago when I never thought I would. If you visit from the beginning of the blog, you can see how far we've come. Just a suggestion. That's a good amount of marker to have on hand for coloring. So if you're intending to color try everything before you sell them. You'll kick yourself later.

I will be happy to answer any questions you have, some of the other folks that follow will be happy to help as well.
HTH