If there is no basement, seek shellter in a small interior room in the middle of the building, like a closet or a bathroom. Opening windows to equalize pressure during a tornado is ineffective in reducing damage. Also, flying glass is a real hazard. You can outrun a tornado in a car. If you're in a car and a tornado is near, get away from the car and lie in a ditch or low area, protecting your head with your hands.
Mobile homes are safe if they are tied down.
If you're in a mobile home when a tornado watch is announced, leave and go immediately to a safe structure. Or be prepared to take cover in a low area, covering your head and the back of your neck.