Well I wouldn’t be doing my job if I didn’t recommend Firebrand Enterprises!
That said, the Horde is full of a bunch of actively recruiting guilds. Feel free to browse any of the threads on the forums marked with an H. And check out the Horde Guild Directory.
And if you’re anxious in general when it comes to roleplay, there’s the Friendship Fundays event, which is geared towards new and returning RP’ers.