Oh, and don't worry about the Photoshop part, it'll come.
- choose something special about the car to highlight, something you like about it
- choose a low angle if the car has a big cabin, and just the opposite
- aim for f11-f18
- aim for 2-6 seconds (2 seconds for the car, wheels, street, 4-seconds for the rest)
- never have the car running
- don't push the car if you can keep from it, park on a slight hill and have the driver release the brake
- if you can show the driver in the shot your stock when up by 50%
There are more, but that'll get you started 
