How and what do I need to set up a private investigation outfit as a business and how do I go about it,?

I want to open a private investigation outfit as a business to investigate cases for individuals, firms, companies, etc. I would like to know what are the requirements, licensing, dos and don’ts, how many people needed to start with and agencies to liase with the whole works, fees to charge as a rookie, equipments / gadgets needed, etc, etc,.