Socks and Swatches
You don't swatch for plain stockinette socks -- you just start. What a liberating concept. If Elizabeth Zimmermann, Nancy Bush and Stephanie Pearl-McPhee share the same philosophy about starting socks, then I should too (the worst thing that can happen is that you end up with a pair of socks that fit . . . somebody). The sock *is* the swatch. Surprisingly, I've been known to get hung up on the details occasionally and not begin something for fear of messing it up and doing something wrong, so the nice yarn sits in a corner, untouched. I couldn't stand to have the Rohrspatz & Wollmeise suffer the same fate, so I chose my needles (Clover bamboo 2.25 mm) and just started. And it's knitting up beautifully!
This weekend while I was working, a customer came in with a pattern for a baby hat and some yarn (neither of them ours, but that's okay . . . sometimes) concerned about not having gotten the pattern gauge and I suggested just starting the hat with the suggested needle size (which she already owned) instead of what she thought she needed to get gauge (which she would have to buy). The worst thing that could happen is that after knitting the hat, it would be too small or too big. The hat would still fit a baby somewhere. She had more than enough yarn and the appropriate needles. Just start the hat. Oddly enough, she didn't seem happy with my suggestion.
At some point, you just have to believe that you have everything you need and that it's okay to make some mistakes.