Let's talk about phones

Okay, I am finally giving in and admitting that I should get a cell phone. I don't know the first thing about cell phones and service providers. What do I need to know and what should I be looking for? A smartphone might be nice, but I'm thinking maybe I should start out simple (and cheap). I think my main priorities would be coverage, voice quality, and battery life. GPS would be nice too, so that I wouldn't need a separate device for geocaching. Does anyone want to add to (or contradict) what's in the CNET cell phone buying guide?