The best book about business models (they talk about “profit models”) is Adrian Slywotzky, David J. Morrison, and Bob Andelman, The Profit Zone: How Strategic Business Design Will Lead You to Tomorrow’s Profits.
The best way of thinking through a business model is not by developing a set of Power Point slides, it is by drawing a diagram. The best guide for doing this can be found in Scenarios: The Art of Strategic Conversation by Kees van der Heijden.
A Business Idea Diagram should be specific enough so that if anybody asks you, “what is the idea?”, you can answer, “wait, let me draw you a diagram”. You should then draw a diagram that is simple enough so you can draw it from memory, but specific enough so that it is unique to your business.