Farm communitiesThe first city in a region often starts out as a farm community. But, as education levels increase, demand for farmland decreases. To keep the city a farm community, start zoning as low density residential and low density commercial. Because of the low density, there is no need to go beyond windmills and water towers. The more educated citizens will commute to other cities for better employment possibilities.
Bedroom communitiesA bedroom community provides employees for the other cities in the region. It's probably the hardest one to make money on. Sims need a lot of services to be happy. To keep the traffic down, you will need transportation. At a minimum, you will need bus stops. Though, I like to do without bus service and just concentrate on trains and subways. As the city and region grow, you will also need passenger train service to industrial cities and subway service to commercial cities. A few commercial areas within the city will help keep the Sims happy -- and help generate money.
Purely industrial or commercial citiesThese are the easiest to make money with because they don't need services such as hospitals and schools. In fact, these cities don't even need a police department since there are no Sims living there to commit crimes. The cities don't even need a fire department. When a fire start, you can plunk down a firehouse near the flames and then demolish it when the flames are out. (You don't even need a road for the fire engine to travel along.)
Mega citiesTo get all or most of the rewards possible in the game, you need a city with residential, commercial, and industrial areas. When planning to develop a mega city, I start with farms and high (or medium) density residential and commercial areas. (Tall buildings won't develop without water, and so I don't see much need to start with low density zoning.) I place the first residential/commercial area in a corner of the city. Then I establish a train link to what will become an industrial city.
The industrial city can provide electricity (a coal-burning plant), garbage disposal (a waste-to-energy plant set at zero electricity production), and jobs for lower skilled workers. The residential city can provide water for the industrial city when it is time to water the city. (Dirty industry and farms produce water pollution which stops water pumps from working.)
As the city grows, you will get some beneficial rewards such as the mayor's house, a farmer's market, the state fair, houses of worship, private schools, and cemeteries. Then as the city grows and the citizenry become more educated, you'll want to dezone farmland and build more residential and commercial areas. When the demand meter shows that the only type of industry wanted is high tech, it's time to start building non-farm industrial areas.
I like to start off by building along the edges of the city map with farmland in the center of the map. When the farmland is dezoned, it provides a perfect place for a city center.
Hold off on a lot of the rewards. I would suggest waiting before building such rewards as the country club, city hall, university, and tourist trap -- either because of the monthly cost or the need for nearby police. (It seems that the larger an area a reward takes up, the more need it has for police.)
Also, hold off on establishing a purely commercial city bordering the mega city until your commercial areas are well developed.
When you do start watering the city and zoning for high density development, it will be time to demolish small police stations and build large ones where they can have the best coverage. You'll probably also want to move the library and museum. (I'd suggest near a college -- for ease in keeping track of them.) You'll need the central space for larger schools for your growing population.
Some notes about transportation:I'm ambivalent about bus stops. Sometimes I think they cause more traffic congestion than they alleviate. For smaller cities, if you decide to use buses, place bus stops along heavily traveled routes to relieve congestion. For larger cities, place bus stops (or, better, subway stops) near residential skyscrapers and also work places. To get a new residential section to develop, place a bus stop near the residential zones. (People will hop off the bus and decide to build a house.)
I think that passenger train stations and the like do more than bus stops do to alleviate congestion. Passenger train stations also provide taxi service.
When choosing an airport to build, choose one that is right for the size of your city. If it's too large, it will drain your finances. If it's too small, it won't develop properly.