The first thing I do is pause the game and look over the map and the different sources of food and raw materials I am allowed by the mission. I list these on paper, what industries are available and all of the trade routes with their costs to open, land or water route, and the amounts and types of goods for import and export.
Once I have this info, I decide what the main source of food will be and what will be my main trade items. I lay my city out in my mind based on the above information. If there is a population requirement, I base the size and number of housing blocks on that. If there is a prosperity requirement, I let that guide me in the level of housing I shoot for. If water trade is used, I'll plan on placing any industries that use imported, "water route" raw materials and any industries that produce goods to be exported by water near the dock. If there is an important housing evolution good like pottery that needs to be imported by water, I'll keep my main block near the dock also.
Once I have the general layout, the following are the steps I follow in roughly this order:
1. Layout housing and main road system.
2. Start producing or importing food.
3. Add temples to blocks. Start keeping the gods happy as early as possible.
4. Have some sort of export good industry started by at least the end of the first year.
5. Open trade route to sell export good.
6. Add different export good industries until city is turning a profit.
7. Add military once the city is making money.
Depending on the mission, you may have to add military much earlier. Hope this helps.
Jimaaten
"May musicians compose songs to you and your name be carved on every public space."