make stuff that sucks that no one wants, throw it out.
make stuff that sucks that you can use, keep it for a while.
make stuff that sucks less, keep it for longer.
make stuff and hey, someone actually wants you to make stuff for them
make stuff better
and so on...
To me, its about making mistakes and learning from them, trying not to repeat the same mistake twice. Then you are bound to get better. There was some quote I heard that if you make enough mistakes and don't repeat them, you will run out of mistakes. It was a bit satirical, but I like the general line of thinking.
A shim is a small piece of wood, chipped to fit into a joint and glued in place so that the joint is snug.
There's a quote by some physicist to effect of, "An expert is someone who has made all the mistakes one can make in a chosen field."