Defending one's self against a zombie is always a harrowing and risky experience, and should never be taken lightly, even in the best of circumstances. The vast majority of zombie combat (despite popular depictions) is usually under the worst of circumstances. Having a gun or a durable melee weapon at hand is always recommended, however when one is caught off guard (like most zombies, before they were turned), one should always know what everyday objects to reach for and which to avoid.
When you are unarmed, killing a zombie is almost impossible without favorable terrain. Retreat, hurling, or shoving objects to keep the zombie from grabbing or biting should be your first priority (one mostly needs to listen to their basic survival instincts and try to keep the zombie as far away as possible). Punches are not recommended since it's more than likely that one's hands will get cut from impact and let in the zombie virus. However, it has been documented in rare cases that a grappling hold (presumably from behind), and a fight-or-flight rush of adrenaline can give ordinary people the freakish strength to damage the spinal column of a zombie with their bare hands. This, while not technically impossible, is not recommended, as avoiding bites are incredibly unlikely.
Kicks are fairly effective at avoiding fatal zombie contact, as zombies have difficulties maintaining their balance. However, kicking (especially under duress) expends considerable energy, and cannot destroy a zombie brain. Think of a shoving (or thrust) kick as your last line of defense (or first, if you have no obvious weapons around you), then flee, or find a weapon
Using one's environment can be critical to survival. If there is a something a zombie can fall into, or on top of that will kill, immobilize, or even make it's pursuit of one's self impossible, recognizing that can save one's life.
Assessing Improvised WeaponsEdit
The first question one should ask is what can be used to shove back a zombie. This way, you buy time to escape, or find better weapons. Tables, chairs, and larger household items weighing over ten pounds are good for this, though they won't last very long.
The second question one should ask is what is available that can break bones. While hardly a dependable long term weapon, things like CRT (heavy) computer monitors, sturdy chairs, fire extinguishers, portable radios, hammers, or maglite flashlights may break a zombie wrist, jaw, or face. Concentrate on bashing weapons - stabbing or slicing weapons (again, despite popular depictions of zombie killers) will not be effective. Stabbing the brain through the eye socket or under the jaw through the soft palette is extremely difficult under duress, and against a flailing zombie. Penetrating the skull can be very difficult without weapons designed to do so (although many heavy tools like hammers, axes, large wrenches and the like might work in a tight situation.
Improvised weapons often fall apart soon after their first usage, as they were not built to endure the stress of repeated employ, like true weapons are. A notable exception are hardware tools such as hammers and crowbars, which are designed to be durable, and to strike materials much, much harder than flesh and bone.