Just put yourself in the place of the character (within the parameters of the world you've read about), use your common sense and be aware of the actions of any partner with whom you engage in roleplay. As long as you're not doing anything daft like trying to be a jedi knight or power emoting (i.e. performing an action that prevents your RP partner from roleplaying back, such as "John stabs Bob and kills him") you should be fine.
They're a friendly lot on this server so if you aren't sure about something, just ask ingame. Even the most hardened RPer will give newbies advice, since improving your ability to RP will help improve their own experience.
Musician, Orator and Composer in The Shades