Each new character gets a new paragraph whenever it is they speak/something shifts perspective and it is usually a good idea to remind the reader that the other people exist when they haven't spoken for awhile if it is applicable ("_____ barked out a laugh at the joke" or somesuch)
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http://firsthour.net/screenshots/suikoden-2/suikoden-2-luca-blight.JPG
The Cult of Personality.