After my first full game, I didn't realize how powerful having a ton of food was until late in the game. I managed to set up a city close to the last 100 turns, that did nothing but food, and suddenly I had more colonists than I could find towns for.
My next game I plan on putting down my first town around a lot of food. If I have lots of water tiles, the first building would be the dock, if not, then definitely schoolhouse so I can train up all the colonists I'm generating into expert farmers/fishermen.
If you make your first city all food, except for perhaps one tile for wood, you will have more colonists than you know what to do with. If you have a expert farmer/fisherman native village nearby, then go with the church for the first building as you wont need to train your colonists internally and this is a good way to gain free specialists early on. Also, because churches loose their punch after the mid game, it's a good idea to have them going full tilt as early as possible and then phase them out later.
As for the second city, I plan on setting that up as a production and training centre for professions other than food production. Sort of a 1, 2 process to funding new colonies.
I will be trying this strategy out later tonight after work, but from what I saw, it seemed quite powerful if I could get it set up early on. In the game I'm almost finished, my army went from almost nothing, to 3-4 defenders per town in a very short time. (Given that I'd set up a big weapons factory before having all the extra colonists)