I've lived in my car for the past year, spent several months living in an SUV a couple years ago. Alot depends on your situation, the vehicle you have to work with, the area you want to stay, etc.
I live in a really chill area, but to sleep, I drive a few miles out of town where no one goes, and I don't have to worry about being harrassed by cops or assholes.
Otherwise, motel/hotel parking lots, 24 hour businesses (Wal Mart, Grocery Stores, Gyms, etc.) Shit, the other day, the cops found a guy dead in his van who'd been parked in a Vons parking lot for three weeks before anyone called.
I've been a mechanic for several years, so that wasn't a problem, but like the others said, defintiely learn at least the basics about automotive technology and maintenance.
If you really want electricity, get a cheap generator, or wire up a deep cycle battery with an isolator. Standard automotive batteries are not designed to be disharged, and just sitting there idling will wear the engine out.
There's alot to say, but I'm not going to write all that now. It's fun though, alot of creativity involved. Figuring out food, cleaning up, staying undetected.
