I can't speak for everyone, but this is the way I've done freelancing work in the past
Twerl makes specific items upon demand, which normally works out as agreeing the item to be made, then visit the shop in question that might sell such, so for clothes either the Naked Bird or Belladona, buy the required item with its description and such so you have the item listed in Des but to RP out buying the materials instead. Then rp out making the item, so arranging for measurements to be taken, fittings and the like, keeping your logs of all of it as proof of work done. When its all done and finished.. give the item to the buyer, charge them whatever has been agreed upon and they can say they have got a handmade item by such and such a person.
A couple of threads that might help out
viewtopic.php?f=216&t=9407viewtopic.php?f=216&t=18951