types of goods-
raw materials
manufactured materials
food

these things can be traded, to keep it simple no different kinds, just these 3. These are traded by trade routes. Trade routes set up by selecting the goods, and either building a caravan or juke, these change to freight and super tanker(better name).

type city
>=buy most
Science>Food
Manfacturing>raw materials
Raw materials>food
Food>manufactured materials

All will need some of the other kinds, raw materials or food depending on what they make. Later they will be more polarized so importing food is very important.

Corporations and Guilds
In early times you have guilds all the way to the corporation tech, which starts corps and they assimilate all the guilds in a number of years in your civ. These can produce goods faster for trade and building units. These can also be hired to take over improvements, see oranges thread, and make trade routes where they provide the caravans but take % of the money made.

Jobs-
People need jobs, everyone needs to be hired to do something or they are unemployed. See "Corporations" thread, its old but you can find it to learn more. 3 everyone is either lower middle or upper class and is hired by either gov, corp, business. If there isn't enough jobs then people get mad.

That's about it, if we need a more complete version I'll type one up later.