One precaution: You can't paint with it in cold weather. The chemical reaction that transforms the water solution into a durable finish will not take place if the temperature is below 50°. (Conventional oil paints don't stick well in cold weather, either.)
Scuff for paint. Once your Mustang is totally stripped of exterior chrome it's time to scuff up the existing paint. The paint shop should do this also, but on the lower end paint packages they won't spend much time here. It's better for you to do it so you know it's done thoroughly.
Basically what you're looking for is a good, solid foundation of existing paint that is stable and still strongly bonded to the car. Many times an original factory paint job, even after decades will meet these criteria.
You'll need a large compressor, not just the typical 20 gallon variety most of us have. This is a 60 gallon, vertical compressor with typically a 5+ hp motor. Then you'll need a decent paint gun (possibly 2; one for primer and one for color) which again is an expense. Then there's the question of where you'll paint the car. Renting a paint booth is best, but can be expensive and hard to find. You can always seal up your garage or shoot out in the wetted down driveway, but you'll inevitably get dirt and moisture into the paint.
Specialist paints also include some exciting new finishes, such as suede effects, metallics and high-sheen lacquers. Judy Smith, colour consultant at Crown, suggests an accent wall in one of these to lift a neutral scheme. Crown's Feature Wall range, which includes eight metallic finishes, nine bright colours and a highly reflective Pure Brilliant White, comes in convenient 1.25 litre tins.
At a minimum you want to remove all the chrome from the car. Take off both front and rear bumpers. If your Mustang has bumperettes that are body color be sure to bring them along so they can get sprayed at the same time as the rest of the car. Remove all rocker, hood and trunk molding. Same for wheel well molding and all emblems. This would be a good time to order some new emblems and attachment hardware. Also spend some time cleaning up all the chrome with #0000 steel wool. Nothing looks worse on a fresh paint job then faded emblems and corroded, cloudy chrome.
In conclusion, this article has really just been a "Painting 101" exercise. I'll be adding more articles on the subject once you get more advanced. It's so rewarding to those who stick with it. My work now sells around the world online. So I'm glad I'm glad I stuck with it. It's been infinitely good to me, I've met the most interesting people....including Madonna! And I am so glad I get to do what I want And ultimately it's so gratifying to leave expressions of myself behind forever. And if the owners then turn around and sell my paintings for a fortune later, then that's the cherry on top for me. I feel lucky to have found my calling. And I hope you find it too. And I hope that every single time you view one of my paintings it brings you a little bit of the amazing joy it brought me when I was creating it.