Stay away from glass enclosed places or areas with wide-span roofs such as auditoriums and warehouses. Crouch down and cover your head. Don't take shelter in halls that open to the south or the west. Centrally-located stairwells are good shelter. Stay away from exterior walls or glassy areas.
Most deaths occur in cars and mobile homes.
If you are in either of those locations, leave them and go to a substantial structure or designated tornado shelter. Lie flat in the nearest ditch or depression and use your hands to cover your head. Be alert for flash floods. Stay away from west and south walls. Store water in clean covered containers.