It is true.. the world of crossdressers is a secretive one.. and it is usually very hard to find people
a) who are willing to be socially active outside the relatively safety of the Internet → does one go out in public, geographic constraints for meeting up
b) with whom there are more shared interests than crossdressing → talking about clothes, make-up, heels and the problems of the CD world should not be the only topics
c) with whom you can have a good time → personalities, mentalities and views shouldn't clash too much
Having said that, I started being socially active on Flickr since 2007.. and I have met a number of Dutch/Belgian CD/TG/TS's. Usually only after quite a few email/chat exchanges where it was clear that there was enough social chemistry to actually meet in person. And through those meetings, I became good friends with a handful of them.
I've also met a few while traveling abroad.. and while one meet-up is not enough for a deep friendship.. I do consider them friends.
And with most people, the contact is only through forums, Facebook and Flickr. I wish I could meet them, but a lot of you all live so far away!
In all of those cases.. a), b) and c) do apply.. to be actual friends is more than just one shared interest.