I mentor a few artists just starting out and I'm often asked about this. Spec work, or the contest model, is never a good idea. I'll explain why, on both counts. ....... The key ingredient to success is the design relationship, getting feedback from your customer, being told what works and what doesn't work. If you can't handle some one saying they don't like your design or even "it's ugly", you are in the wrong business. Designers need a thick skin, and often we need to push our customers to tell us what they don't like. Only then will we have a stunning design.