Upper floors are unsafe. Avoid rooms with windows. If you live in a mobile home , even those with tiedowns, seek more permanent shelter. Go to a friend's house, or a nearby structure with a basement. As a last resort, go outside and lie flat on the ground in the lowest depression available with your hands over your head.
Mobile homes are unsafe.
In an automobile , don't try to outrun a tornado. Get out of your vehicle and seek a safe shelter or lie down in a low area with your hands coverning your head. Don't seek shelter under an overpass because most don't provide adequate protection. If you must, drive at right angles to the storm. The best bet is to avoid travelling during severe weather.