Unless you have a well-designed site, it won't do anything to encourage customers to use your service. Sometimes, a very poorly designed site can actually hurt you by making you look sketchy.
Gold swapping also has very little use for a website. A gold seller can receive payments through a website without actively engaging a customer. Gold swapping always requires someone to manually accept a transaction, so the website provides very little utility.
If I was a gold swapper, I'd find all sorts of forums to make threads on. Keep in mind that some sites which do not allow RWT (GP for $) may allow swapping.