Be very careful around black plastic. The wax will permently discolor the black. It's ok if you don't wax the paint with in a couple of inches of the black plastic. In fact feel free to use masking tape, but it's easier to keep a safe distance. This includes when you rub off the wax.
I was lazy today, I only waxed the hood and front bumper cover. I didn't wax the rest of the car!
This is where all the bug impacts are and they don't stick as much.
One could argue that waxing a car is a waste of time and money. So if you don't wax it, don't feel bad. It isn't like you decided to never change the oil!