There's nobody who will give additional discounts for group buys if everyone gets the same size, right? Murls and Noodles, I'm ideally a 39 jacket and a 31 waist but often a 40 shoulder (Epaulet Weller, my Coppley Donegal tweed) gives the best fit.
On the other hand, this may explain why size 31 trousers in popular fabrics seem to sell out instantly from SF vendors.
As should be apparent from my recent efforts, it would be hugely hypocritical of me to offer advice of any value on this question. Several people suggested getting a self-timer app for the iPhone to me, and I think they were right on the money, but finding a good source of natural light is the real key to good fit photos.