In addition to the O/Os system Mith linked you to, there is also a forum entitled 'Ons and Offs - Lords' in the 'General Sexiness' section of the site. Here you can start up a thread that gives as much information as you wish about your RPing preferences such as what kinks you enjoy and dislike, genres, settings, pairings, list your own characters, preferred game systems... even a section of writing that shows your writing style. You can make your personality come out in this area which you can't in the system Mith showed so it's useful to maintain both side by side.
Anything you wish can go there that you think will help other site members learn things about you that will make them want to RP with you! And don't worry, other members cannot/do not post in others O/O threads.