Q: What are the items available on the market to protect and prevent myself from being attacked?

A:  First, use your brain. (Get the book, "Gift of Fear" by Gavin deBecker). Situational awareness and a tactical mindset (sometimes called "street smarts")is the best prevention tool. The best way to gain this wisdom is to have experience. And the best way to have gained experience is to have training or, unfortunately, to have experienced multiple defensive situations. This is one of the reasons most bodyguards are ex-military or ex-cops.

Second, use a weapon. The rule of thumb is to use a weapon against another weapon, against multiple opponents or when the disparity of force is so great that a reasonable person would fear serious injury. All weapons fall into the categories of impact weapons, projectile weapons or bladed weapons. (I would put OC spray and stun guns in the projectile category). Weapons I would not recommend: Ninja key rings, stun guns, keys stuck out from between your fingers, kubatons. I like OC spray (don't count on it to subdue an opponent, use it to distract your opponent) and a high-quality handgun.

The levels of security I recommend to my students and clients fall into three layers:

1. Psychological -- awareness, alertness, putting the attacker on notice that you are aware of him and cannot be surprised. I tell my students that "a tactic recognized is a tactic neutralized." Practice looking at people so they see that you have noticed them. You don't have to stare them down or "maddog" them. Just a neutral look held long enough that people know you are aware of them and you appear confident.
2. Proximal -- use of space and barriers to control the distance between you and the attacker. Distance buys you time and time buys you safety when recognizing and reacting to an attack. This can be as simple as keeping your doors locked or as different as running around a parked car in a ring-around-the-rosie fashion. (Don't laugh, it might look somewhat comical, but I have seen it work for real in the street two different times).
3. Physical -- the use of movement or force in evading or defending against an attack. Empty hand defense requires training. I like Brazilian Jiu-Jitsu, Muy Thai, Jeet Kune Do and some of the more comprehensive traditional martial arts. I hear Krav Maga is worth checking out, but I've never met a real practitioner so I can't give a personal recommendation. Weapons training should be conducted under a qualified instructor whose program includes scenarios for lawful use vs. unlawful use.

In the end small fish are always attractive as prey for bigger fish. So, unless you look and act like Stone Cold Steve Austin, you are a potential target. But, when you have the will and the means to fight back, you will find a number of criminals will break off the attack. It's simply not worth the effort for some. The flip side is that, if your defense is flawed or ineffectual, some criminals will intensify their attack, infuriated that you were "dumb" to fight back.

So, you need to train and get prepared. Once you start, your life will change in remarkable ways...