A few years back I picked up my first issue of ImagineFX and saw that they held weekly and monthly challenges for artists of all skill levels. So I lurked on the forums for a few weeks, and -- after coming to the conclusion that the participants would not bite and were, in fact, very supportive and helpful to each other -- I took the plunge and participated in my first challenge.
The experience was grueling, since I was unused to dealing with tight deadlines, and frightening, since I'd not had my work critiqued by strangers in nearly two decades. But by the end of the week, I'd produced a piece unlike anything I'd ever attempted before, and learned more than I had in years.
The amount of advice and encouragement I've received over the years from the excellent community at ImagineFX has made me a much better artist in innumerable ways. And I've made a few friends along the way, too.
So, if you are an artist of any skill level and seek to become better at it, I strongly encourage you to get over there and try out a challenge or two.
Here's a direct link to the Challenges section at the ImagineFX forum. Good luck and happy painting!