It depends on what you kind of RP you are looking for, so you'll have to answer that question for yourself first. Usually, it breaks down into those who enjoy telling a story with someone else (cooperative or interactive storytelling), or people who want to experience a story from a particular point of view (playing a particular 'role', you might say).
MMO RP guilds tend to be the latter, but also mix in a great deal of game and social elements that may or may not be your cup of tea. I tend to prefer one-on-one RPs myself, using some sort of chat program or messaging system. Since you're posting on this forum, I assume you want to satisfy some ryona desires too, and it would be good to figure out and describe what those are. I'd recommend taking a look at the Looking for Roleplay thread to see if you can answer some of those questions there about your desires, and the potentially posting your own ad on the thread too: