For a few hundred euros (more expensive or cheaper, depending on country), if you want you can find the gloomy suspicious persons, touting confidently their ability to kill anybody. Usually they are drug addicts, petty criminals, aggressive morons, or just people desperate to earn anything legally. Often the avid players caught in the debt trap consent to this kind of thing. They act roughly as follows: wait for the victim in a safe place (usually overnight), and then inflict numerous blows with an axe, a metal bar or simply a club. A more nimble one can use an awl, a knife or a screwdriver, but it requires at least minimal trainings.
This category of killers has only one advantage - the price, but it does not compensate its numerous disadvantages. It is not a good idea to get involved with drug addicts and morons in principle, because they have their own reality where they can easily mistake the target or even forget about their obligations. Moreover, if it comes down to it, yet known who will win, then the victim has a good chance of winning. These double-trouble killers work either alone, or in a group of two or three, and no one could speak about well-organized operation. Therefore, if the victim does not appear in a proper place, the deal is off. Of course, even the most inexperienced bodyguard will become an insurmountable obstacle for them.
Smarter criminals are usually rich with surprises. They often come to the customer, say that the police raided the crime scene, and require a lot of money to disappear without informing the police. As a result, they receive a double fee for the murder, which they were not going to commit. Such frauds have options. For example, they can say that the potential victim has serious criminal links, and, of course, it requires money to hush up the deal. The killers of the lowest skill level are accepted for killing the same morons like themselves if any problem does not sabotage the plan.
There is a kind of advantage of these "experts" - a convenient eventual elimination of them. Killers constantly face this problem, so they usually require security. The security is as bad as the killers themselves are. Some people find it convenient to turn contract murder into a common attack of drug addicts, and then to kill the perpetrators fearlessly.
However, you should not confuse this category of murderers with simulators of accidents and assaults. They belong to experts of higher professional qualifications, and to eliminate such agents with impunity is not going to work out. In some professions, the development of professional skills occurs in the spiral, and the highest point of perfection looks like initial. For example, a skillful prostitute looks like a shy and innocent girl, experienced true passion first time in her life. In martial arts, the situation is the same. The most dangerous killers look like silly and helpless nerds or completely degraded individuals from whom you expect nothing worse than clumsy kick in the teeth.
The best for professional killer is to be funny. Neither indifference nor pity or disgust do not relax as the laughter does. On a subconscious level, people unable to be afraid of someone who makes them smile. This is coulrophobia - fear of clowns. The principle of maximal contrast works, when danger lurks us where we least expect it. Analyze similar themes in the works of the horror genre, and you will discover many interesting facts. What could be worse than the evil, suddenly coming from those from whom we expect protection, care or entertainment? A gentle lover, suddenly turning into vampire, a clown, who suddenly emerges a predatory grin, or a mom, who turns out to be a scaring ghost. What do you think about the situation, when a patient on an operating table suddenly finds out that the surgeon is actually a maniac? A professional killer must have an extensive and deep knowledge in psychology even in areas not connected with his profession. He must be a great master of pretense and lies. Then he will easily be able to approach anyone, strike and evade justice.