How do you create your revenue?

I'm thinking of creating a network of informative sites on historical/influential people and was wondering how one would go about profiting from such a venture. I plan to try and develop it enough so that traffic is good, and then possibly sell ad space. But what should i do in the meantime? Adsense?

I have no clue what i'm getting into, i suppose i should stop and think about it before i go any further.

Any information would be great.

Jeff, Have a read of the inspiring Chris from sitepoint (or websitepublisher.net) story of how he got started. He started by making a network of literature sites, just go and have a look at how he did it