Remove everything possible from the room. Anything that can't be moved should be placed in the center of the room and covered with drop cloths. Remove electrical outlet plates and any wall fixtures. Move out area rugs and cover carpeting with drop cloths. Apply painter's tape to any trim or other features you don't wish to paint or drip paint on.
If you are removing fixtures, make sure to turn the power off at the circuit breaker and cover the breaker switch with tape so as to avoid electrocution. This serves as a reminder to others not to restore power. Run an extension cord into the room for work lights.
Because fumes from paint can be odorous and overwhelming, ventilate the room by opening windows or installing a box fan in an open window to pull the fumes outside. Open another window just outside the room to allow for cross-ventilation. This minimizes dust and fumes throughout of the rest of the house as well.
Inspect your wood paneling for any protruding nails. You don't want to run across one of those while you're cleaning the walls. To avoid injury, tap the nails back in with a hammer to make them flush. While you're at it, check the paneling for any loose or damaged panels. If you find loose panels, simply nail them back to the wall with paneling nails. Severely damaged panels may have to be replaced.