Modeling can help, and it sounds like you may be doing some of that already. When I color with my son, I purposefully color outside the lines and positively talk to myself out loud through my "mistake" in order to help DS3 develop coping skills. Also, eliminating words like mistake wink and creating a new dialogue when something happens, "oops, I colored outside the lines...how frustrating...it's okay, I'll keep trying" and commenting throughout on effort.

Have you read the book "Beautiful Oops"?
http://www.amazon.com/Beautiful-Oop...391037141&sr=8-1&keywords=beautiful+oops

Perhaps you could read the book with your DD and then set up some art projects that tie in directly to the art activities modeled in the book (turning mistakes such as spilled paint or torn paper into wonderful, new creations). Make a game of it...funniest oops, etc. Frame it afterwards and make it part of her new story of herself as someone who keeps trying.

Also, eliminating or reducing pre-set play (coloring books or drawing a house or toys that need to be followed to a t) and more open-ended may help. Try swirling multiple paint colors in a shallow tray...no mistakes there just the wonder of creation.

I personally realize that this is a much bigger issue, but perhaps tying into her existing interest in art may provide the ideal context to begin exploring this issue.

Good luck!