If you want to sell your designs you must watch this presentation from the 2010 Blender Conference in Amsterdam by Andrew Price AKA Blender Guru. It may be about being a digital artist, but the same rules apply to all independent designers whether it is CG, Jewelry, Product, Furniture, Graphics, or Needlecraft.
If 35 minutes is too much of your time (I listened while doing other menial tasks (not work related)) you can always read the article on his blog..
If you do not have time to watch or read, here at least is a summary of what you need to do to succeed. Step 2 could be replaced by having an exhibition, market stall, trade fair, Shapeways shop, PDF portfolio, press pack etc etc…
Thanks to Bart for the heads up.