One favourite resource of mine regarding creativity is Originality in Design by Nick Pugh (http://thegnomonworkshop.com/dvds/npu01.html), where he describes his process of coming up with original design, as applied to drawing. One interesting thing he brings up is that sometimes, if you know less about something you become more free in your thinking about that subject. So experts face a real danger of becoming stuck in their way of thinking. There is a lot more in there and it is worth checking out for the discussions alone, even if you aren't into drawing.
