Painting a car well is what makes the whole artwork look like it was done by a pro. When I started drawing cars I focused to much on painting the cars right instead of looking at the proportions of my car painting. So before you start shade and paint be sure that you are satisfied with the cars lines so far, because once you start paint and shade it will be very hard to change any lines. So if you are absolutely sure, then let’s start shading the car.
One big tip here is that you start at the upper left corner (or upper right corner if you are left-handed). This is because it reduces the risk of the car paintings to get all messy. So start from the upper corner! Think about how you need the whole painting to look, try to get a image of it and then you start slowly adding with your pencil this to the background. If you need reference photos then go a head and get those, these will help you not to mess up to much on the background proportions. Don’t start with the darkest area, instead start coloring the lighter area of the background of you car paintings, and then go to the darker areas gradually. Then when the upper corner is done, then start moving the center area of the car painting and continue with that area and then next and so on.
A trick for making the car look very well shaded is to exaggerate the contrast. Where you need it to be black, be sure to make it black and not any “grayishblack”, this is a little trick lots of gifted artist miss out on. Same goes with the different shades on the car, going from dark to light, be sure to really make the dark areas dark and the light areas light.
And remember to take any breaks from your car paintings, don’t rush it and try to get it all done in an hour or so. Take a break after an hour or so and then come back later and you will probably spot any small mistakes that you did not see while you were doing them! And my last tip is the most important one: Be sure to have fun!