I stopped using Sculpey III and started using Premo and Kato
I discovered sanding....(but we all knew that was going to be a familiar theme, didn't we? :) )
Very much along the same line as da Puffin's : when I stopped trying to recreate what other people were doing and started experimenting and moving in my own direction creatively.
When I allowed myself to make ugly stuff
When I started learning about, instead of being intimidated by, artistic "basics" like color, shapes, line, etc..
When I allowed my natural goofiness and sense of humor to occasionally shine through (remember my googly eyed bat?)