Although fast action is vital when a tornado strikes, knowing what NOT to do is just as important as knowing what you SHOULD do! That being the case, let's take a look at tornado safety in the home.
First of all, let's look at what you should NOT do! Specifically, you should NOT open the doors and windows in an attempt to equalize the air pressure inside and outside the house! Although this procedure was recommended for many years, that recommendation was summarily dropped in the wake of the so-called "Super Outbreak" of April 3, 1974. (An "outbreak" is defined as the appearance of multiple tornadoes in a given area at approximately the same time.) Up until that time, it was believed that tornadoes caused houses to "explode," due to the powerful updrafts (at speeds of over 100 miles per hour) generated in the tornado funnel. The studies of ground damage which took place after this disaster (led by Dr. Ted Fujita, of the University of Chicago), however, proved beyond all question that this simply does not happen. Rather than exploding, the houses are simply being blown over with massive force, although, to the untrained eye, they might look like they're exploding. (If such explosions actually were exploding, the debris from the houses would be scattered more or less evenly in all directions. Dr. Fujita's studies, however, showed that this simply is not the case.) In fact, Dr. Fujita's studies showed that, rather than help save houses, trying to open the windows and doors, actually endangers people's lives, because they waste time that should be used in seeking proper shelter from the tornado's winds. Besides, the tornado winds will most likely blast the doors and windows open anyway, as Dr. Fujita's studies and simulations clearly demonstrated.
Okay, we've established that opening windows and doors before a tornado strikes is worse than useless as a safety measure. So what SHOULD you do? The basic rule of thumb is to put as many walls between you and the tornado as you possibly can. If you have an underground shelter, such as an old-fashioned storm cellar, that is ideal. A commercial above-ground storm shelter or "safe room" is the next best thing. If none of these is available, then a basement area is a good place. If, as in so many homes these days, you don't have either a basement or a safe room or a storm cellar, then a closet or bathroom (providing it does NOT have windows) is most likely your best bet. (A bathroom without windows is particularly good because the extra framing required to hold the pipes and plumbing fixtures gives the walls of the bathroom considerable extra strength.)
If you're taking shelter in a bathroom, the best thing to do is to get down in the bathtub, curling up in the so-called "tornado crouch" (that is, getting down on your knees and elbows, face down, covering the back of your neck with your hands and lower arms). If you're in a closet, assume the "tornado crouch" position as described above, facing the innermost wall, particularly if you're in a so-called "walk-in" closet. In any case, you should have shoes and socks on to protect your feet, a helmet of some kind (even a skating or bicycle helmet will help!) to help protect your head, and blankets, heavy coats, or even a mattress to help protect you against flying debris. If you don't have a helmet, then pull a metal wastebasket over your head. Since flying debris is the major cause of deaths and injuries from tornadoes, such precautions can literally mean the difference between life and death!