However, if you are used to working nine till five and like to have routine in your life then perhaps you should reconsider. A few cold, caffeine-fuelled nights staking out a target on behalf of your client and maybe that office cubicle doesn't look so bad after all.

Still interested? Then you are going to need specific training at a private investigator school as the profession is no place for amateurs and many US states require investigators to be licensed.

Don’t let the word "school" frighten you off – unlike studying at high school a private investigator course will involve studying a narrow field of expertise that is going to be of some interest to you.

Attending private investigator school will enable you to pick up years of hard-won experience in a short time as you learn the techniques of private investigation. Think that all it takes is a camera and a telephoto lens to become a private investigator? Think again.

There are methods of surveillance to learn, techniques on how to follow your subject, how to disguise yourself without causing suspicion, how to use modern bugging technology, online investigation and much more. You will also need to know how to gather evidence and what evidence will stand up in court.

There's also the fine line between legal and illegal surveillance and on a private investigator course you'll learn the difference. There’s no point invading your subject's privacy to gather evidence when your client cannot later use it in court because you obtained it illegally. Your client could lose the court case due to insufficient evidence, it would certainly damage your reputation and could even lead to you being sued so these are vital lessons to learn.

On the other hand, the rewards are good. Private investigators are well paid and the job is different every day. But what private investigators really do is solve their client's problems – and they can make a difference to peoples lives.

How about re-uniting a divorced mother with her young daughter after the father has run off with the child during his day of access? Locating the birth parent for an adopted client who has always dreamed of finding his real mother? Or running a background check and discovering that the nanny employed by your client to look after their children has a violent history?

Sure, the money's good, but you can't buy that kind of job satisfaction.