I just bought SimCity. I'm going to learn how to play a little before starting a city on a Bay 12 server and ruin everything for everyone. My username is pilgrimboy.
Plus, I have this desire to be hated by many gamers.
DON'T UNDERESTIMATE THE URBAN PLANNING INVOLVED IN THE TRAFFIC OF YOUR CITYThat is pretty much the destroyer of the vast majority of cities in play right now. That said,
Don't expand your density too fast; remember that you can either make a large amount of residential early on and then upgrade the density of only a very small portion of it, or make a small portion of residential early on and then just upgrade the density of that. Either way, you need to control the amount of people coming into your city carefully, because treating it flippantly will quickly lead to a spiral of disaster culminating in your city basically becoming the setting for Escape from New York.
Also, as I've previously mentioned, there seems to be a bug(?) currently where only about 10% of your population are workers at higher populations; plan your industry and commercial in relation to that so as to not face a worker shortage loop.
-Edit: don't be afraid to just try a few cities and fail catastrophically. They'll give you far more understandable-in-practice advice than people like me sure could. If you're playing with multiple people (I am) just talk it out with the others and work out with eachother that you might have to do a few practice regions together before you really settle into a region where things go 'right'.