Ask YC: Resources for learning about revenue models?

Does anyone have any useful reading about the fundamentals of generating revenue? My understanding is limited to choosing subscriptions vs. advertising, or a combination of the two.

How do you make money off of advertising? What are the advantages and disadvantages to both? Is there one that is better than the other depending on what stage your company is in? Is it as simple as asking potential users what they would pay for it?

Thanks very much.