yanner39
Emperor
On Epic or Marathon, warrior rushes are VERY viable on Prince. If you find a neighbor is quite close by, you can switch all production to warriors (working 3 tile), build about 4 or 5 of them, then conquer the nearby capital. The AI almost never has more than 2 warriors guarding their capital this early on. Having 2 capital class cities THAT early is almost always a win as long as you don't muck up the rest of your play.
I would be careful not to become too comfortable with warrior rushes, though as Monarch AIs start with archers / Archery and such strategies are only desirable in extremely fringe situations.
Other than that, everyone's advice here is very good.
On Specialization: Improve tiles in the city's fat cross with a common goal. IE if you have a lot of riverside grassland and a food resource, that's a great cottage spam city. Have your workers improve riverside grassland with cottages and allow the city to use the food resource to grow into new cottage tiles quickly. In that city, you should concentrate on buildings that increase the output of the cottages (library/university/observatory). A granary is almost always a must-have in economy cities to allow them to grow into new cottages even more quickly and to fast-regrow cities that whip their libraries/universities (which I encourage). If your city has a couple food resources and lots of hills/brown tiles, this is a good production city. Have workers improve the food resources, put farms down on grassland tiles (keep in mind you can spread irrigation post Civil Service) and put mines on all hills and workshop on brown tiles. Always count your potential food in these cities and make sure you have enough to work your tiles. In this city, you should focus on granary (for growth), forge, barracks, factory, levee, power plants (if you get that far). One of these type of production heavy cities should house your HE for soldier-spam.
You don't really need to specialize ALL your cities. Usually, in my Emperor games, having a strong cottage-spam bureaucracy capital with Oxford, 2 more economic cities, HE city, a GP Farm, and 3 cities (building either troops for war buildup or wealth for high slider) is all i specialize. The rest of my cities end up as hybrids adding a bit of , , and each.
I can vouch for this advice. Blitzkrieg gave me this advice a while back and it works very well. I've had a number of successful warrior rushes and gotten nice land because of it. The only time I wasn't successful is when I was probably too far (still have trouble judging what is "close enough"). I realize warrior rushes aren't possible past Prince, but it gave me the opportunity to practice.
I still play on Noble but I'm pretty sure I should move up. What I find encouraging for myself is that the great advice being given here are things I already do well (well I still have problems with city placement).