Thought I show how I drafted a wing pattern, whilst I was drafting a pattern for the SS15 range. (Full pattern will be up shortly).
A general rule that I always follow to fit the pattern (unless instructed otherwise by a buyer) is that the strap on the wing (a medium) is 5cm away from the hook and eye. With this in mind, it then becomes quick to draft a pattern for fits rather than trying to work it out all the time.
It's shown it better in the computer drawing above.
Hope this helps those who like to draft their pattern by freehand. Apologies for the poor picture, took it in a rush before I cut it out and got it fitted.