I agree with Ryika about farms standing head and shoulders above other food improvements as the optimal strategy, but... What incentive do you have to pursue *the* optimal strategy, except OCD? This isn't CiV Deity, where you mishandle some part of your game and the AI beats you by 20 or more turns. If you can repel the AI militarly, you can do pretty much anything you want. Any strategy that doesn't create a huge affinity gap between you and the AI is viable. This, to me, is the main issue with the game right now; not enough inertia, not enough challenge, and the AI can't really catch up with the player.