Lightning causes around 100 deaths in the U.S annually, more than hurricanes and tornadoes combined. When a thunderstorm threatens:

• Don't use the telephone except for emergencies. Avoid using other electrical appliances. 
• Do not take a bath or shower.
• Avoid contact with all metal surfaces.

IF CAUGHT OUTDOORS:

• Get inside a sturdy building. A hard-top automobile with the windows up also offers fair protection.
• If you are boating or swimming, get out of the water immediately and move to a safe shelter away from the water.
• Don't stand underneath a natural lightning rod, such as a tall isolated tree, a telephone pole, or a large radio antenna. In a wooded area, seek shelter in a low area under a thick growth of relatively small trees. In open areas, go to a low place such as a ravine or valley.
• Get off or away from tractors, metal farm equipment or small metal vehicles such as motorcycles, bicycles and golf carts. Stay away from wire fences, clotheslines, metal pipes and rails. Put golf clubs down.
• If you feel your hair standing on end or tingling, squat on the balls of your feet with your head between your knees. Do not lie flat.
  
  Sources: The Austin Office of Emergency Managment and the Norman National Weather Service Forecast Office