Since I had, um, expanded a little since I bought the pattern, I had to alter it for a slightly larger figure, which meant I had to alter the collars, too. I copied the front piece onto craft paper, slashed it in the center of the collar area, spread it to the desired amount, added paper there, and I had my new pattern size. I also added a tiny amount to a few other seam allowances. I found the sleeves to be a bit tight in the bicep area, so I added 1/2" there, too.
I also made a Gainsborough hat, a big fichu, and a huuuge cap of doom. I made up both patterns after looking around the internet for ideas on shape and size.