I guess it depends on where you live. If you live in a relatively big city, there are bound to be certain places where T-Girls hang out, and I dont mean just those who "work the streets". There would be some T-Girls that live normal lives. So I guess knowing and a lot of luck, you know... Cos you might think she's genuine, but then you figure out she was just playing you.
Another way, pretty much proven (not to full extent) is online dating. I was very skeptical towards it, and after getting burned by some of the websites (financially... most of them require you to pay fee in order to communicate with T-Girls or get their contact information), I found one website which, well almost changed my life. Not to say that they are all looking for love and marriage, there will be some looking for "sponsors", but I was pleasantly surprised by the number and quality of a number of them.
So patience and luck