When I can do 8 or 10 groups of illustrations like the one above per day
and finish the entire book cover image in 2 or 3 days,
then I might have a shot at the big time. I love the fact that people enjoy my work, but I am also realistic about the fact that the professional world of design and illustration has some pretty high standards and some very tight deadlines. Sure, I've got a whole other full-time job to keep me busy, but I still know I need to greatly improve in both categories.
To that end, I'm actually going to start doing some "sketch of the day" exercises, possibly even start participating in the SOTD forums on CGTalk.com and elsewhere. You don't improve without practice, so I'm gonna start trying to get as much of it in as possible on as much diverse subject matter as I can. I'm confident I'll get there eventually.