Actually i always have two workers per city WackenOpenAir.
1. here is how you micromanage(you may already know this). anyone correct me if i'm wrong:
when you open up your city you have cities. i'm guessing you know about special citizens and labors. move one of your laborers to an open spot. know check how much it produces compared to the before tile. if your in the beginning of the game you should always maximuze the amount of food you get. the more food you have the more citizens you have. the more citizens you have the faster you can produce commerce improvements. also the more citizens you have the more tiles you can work. the more tiles you can work the more money, shields, and food you get. so you see the point that food is important to stimulate your economy for gold and maximum growth and production. if you have a resource you should try to work that. resource usually give you much more benefits than anyother square regardless. but if you are going to shrink because of the resource being worked dont' work the resource. you can always work the resource later when your city is bigger. another important rule of micromanaging. irrigate food resources and mine shield resources. this will bring much benefit to your civilization.
another rule mine green and irrigate brown. this rule optimizes the amount of shields and food you get. this is a basic review but if you want more you can read this excellent article written by Trip:
http://www.civfanatics.com/civ3acad_food.shtml
also read the rest of the war academy to get up to speed. it will greatly benefit your civ experience
hope this helps