The recipe is very easy actually. Pick a business you think you'd be competitive in, and apply for a low level position at one of your competitors. Customer support, mail room, whatever you can get. If you went to a top university or have an impressive resume, leave that info out of your application, it will only raise red flags. Getting the position will more often than not give you unfettered access to all the competitor's proprietary info including revenue, margins, sourcing, expenses, as well as identify areas where you could improve upon what your competitor is doing or make things more efficient. When you have a good grasp of the business and a roadmap in mind, quit and do it yourself.