For those playing along at home and considering bespeaking ties by mail without the aid of a professional and a good mirror, here is a pro tip: order the same tie, preferably a solid, but not too dark, as it has the illusion of looking slimmer than its dimensions (try a medium brown, it will be easy to pair with your existing wardrobe when you conduct the test) in maybe three to five differing widths and lengths.
Go for the cheapest construction option and collect your four nominally identical ties. Test them out in sequence to determine which dimensions look best on you. When finished, give the experimental ties away as gifts and resume ordering your new ties with the dimensions you know to work.
*It is advised to have nailed down a good shirt and suit pattern before doing this as it can skew your results greatly.