I'm playing my first game and thought I'd share a couple things that I've just learned (don't know if these will hold water for the rest of the game but sharing in hopes others will reflect with me on whether this is tractable or not).

At first I was really pushing some big cities. Trying to get cities over 6 or 7 is a major chore. It starts to take a lot of shuffling around of food. At first I didnt realize I could plop a city right next to a native settlement and just buy use of their land. Once I realized I could expand a bit more in my localized area I started dumping my non-specialized colonists and mis-specialized colonists from the big cities and expanded - created a lot more colonies. This allowed me to have several outlying cities which I improved for food production sending food into my larger cities - now it is much less of a problem to prop the larger cities up.

The advice here is to push inland early and get settled on some nice food producing squares. Improve the farms around these cities then IMMEDIATELY start sending missionaries to nearby natives until you find one that can teach Master Farmer. You then have inland cities which can be producing +20 food per turn to a) be colonist factories or b) send food to major coastal cities.

Seeing how this works out...