Hi, it's difficult for me to explain in english, because I'm german
So I give you the link to the ArtRage forum. There you will find brushes, stickers, stencils colorsets and much much more. There also is a "Tips & Tricks" area, I learned a lot from this page. If you are not successful there just let me know, then I'll try to write a little tutorial to help you with your problem. In short, the behavior of color is set at the small "Settings" Tap found over the brashes panel. Here you can handle "Thinners, Loading, Color Bleed and so on.
The Link to forum: Brushes and more
[link] Tips and Tricks (with Tutorial list)
[link]