Ive never done anything special with my Samsung 63" Plasma. I turn it on when I want to watch it n turn it off when im not. Heck sometimes it stays on for 8 hrs. Ive had it for over a year and its fine. Actual burn-ins r rare these days but still possible. Stuck images r more likely and can be fixed with the screen burn-in proctection that is built into all Plasmas.
Ive watched it with all kinds of content, widescreen with black bars and HD with side bars, never had a issue. I have even paused my bluray player but my player is good enough so that it will either have a moving logo or it will simply turn off when it is paused longer than 5 minutes.