proper ventilation
You do need to make sure it gets proper ventilation. What sometimes happens is people put it on the lap, on a blanket or pillow or something and that pretty much plugs up the backside vents. THAT is not going since the hot air has no easy place to go. So, make sure there is SOME space underneath and you are fine.
Also, the foot plugs are pretty good sized, so the metal won't scratch the surface of your desk.