Want to Become a Private Investigator? Learn What it Takes. There is a fundamental ("must have") level of investigative knowledge and skills that successful private investigators possess. These include knowing the rules and regulations of the industry (including licensing regulations), where and how to obtain information, how to properly gather and document evidence, how to interview people, and how to properly report the results of their work. I developed this manual with what I believe specifically addresses vital matters with the rock-solid up-to-date advice and steps necessary to actually become a private investigator.