I started posting Art Adventures to keep myself motivated, but I have also tried very hard to keep the supplies simple so you can stay motivated too.
I don't often present projects where there are a lot of complicated steps to follow so your child makes a predetermined mini masterpiece. I think when we focus too much on that (and showing kids an outcome that only an adult is likely to achieve) it is part of the reason so many kids grow up thinking they can't do art.
To me, the point of doing art with children is not about the finished product. But, rather, it is about the enjoyment of the process and exploring creativity. If it turns out a mess, but the child enjoyed, it's still a success in my book.