I’m not sure of this (I haven’t tested it), so you might have to experiment with some of your favorite clients (or non-client contacts). But when someone recommends you make sure they choose the second option, with you as a service provider, like this:
It should be as easy as that. Why? Well, according to the note at the bottom of the Service Providers page we read:
How do I get listed in this directory?
To be listed in this directory, simply ask your clients to write a recommendation on your behalf. Request a recommendation.
Note, I don’t recommend that you use the Request a recommendation link! I don’t like it, and I don’t like getting recommendation requests that way!
Also, at the top of any page drop down on the Service Provider option, and you see this:
So I’m guessing it’s as simple as someone just recommending you… but make sure they choose “service provider!”