Actually, the guide isn't bad, and the idiots in this thread are of questionable intelligence (Yes, that's you, WN1 Hit. I've seen thousands of your posts, and you've never once made one that is worth reading.)

While it is true that most of your food will come from L10s or L5s, selling excess lumber or iron is a good way to make additional food. With a good set of lumber and iron cities, and what you are getting from the NPCs you hit, you'll never have to worry about the lumber/iron anyway.

Anyone who is patient can feed the lumber/iron needs off the market anyway. It takes me very little time to double my resources, using buy and sell orders.