I finished my Business Casual socks. They came out great and I'm learning to make my socks fit better!
My feet are a pretty average size so you would think I would be pretty safe making the "average" sock - as specified in many patterns that is "women's medium". For the most part this is pretty much true....but...I do have longish feet so I usually add some length to the toe...and I do have small ankles so I usually add some tight ribbing to the tops and a bit of length too.
These changes are pretty easy but the sizing I couldn't work out was the ankle? heel? see, I don't even know what it's called. My socks don't fit around the diagonal of my foot, from the bend at the top of my foot to the back of my heel. I thought about it a bit and I worked out that adding a few extra rows to the heel flap would add a bit more fabric at the point I needed and, indeed, these socks fit great!
And here's a picture: