I’m no expert, but I’ve been jumpedafew times and found myself inahandful of fights and I’ve usually come out alright. I’ve also hadalittle training. The simplest advice I’ve given others is to make clear that you are willing to do whatever is required to defend yourself, then follow through. Very few attackers are dedicated enough to continue after gettingathumb through the eye or repeatedly stabbed around the throat or gut withabroken piece of wood or keys. That said, this is actually much more difficult than it sounds. Most people find violence very unnatural, because they have little experience with harming others. It is therefore important to understand what you are psychologically capable of doing in your own defense. Even professional boxers and martial artists continually train to overcome the natural hesitation involved in attempting harm someone else. In fact, one sign thataprofessional fighter is wearing out is that they’ll start pulling their punches or hesitating, so even at that level, violence requiresagreat deal of focus which is difficult to maintain when exhausted or hurt. The problem is amplified whenaweapon is involved. Stabbing someone with your keys is indeed effective, but it also involvesasubstantial level of psychological commitment since it may actually kill someone. Most people will try every alternative before following through with that kind of defense. If you intend to pursue this kind of violence asaprimary means of self defense, consider seeking some training. There are many martial arts programs which focus as much on conflict avoidance as on response.Irecommend that, since violence is not pleasant and should probably be avoided. Also, look for programs in which techniques are trained against active resistance.