If you decide to do your own body work discuss it with the paint shop first. They'll probably have recommendations on the type of primer you use. Some brands will be more compatible with their primers or color coats. The rule of thumb is to stay within the same brand of paint, both for prep and color. Even the cheapest paint shops typically use a brand name on their intermediate and higher paint jobs. Find out what it is and use the same brand as your primer coat. This will ensure you don't create adhesion problems for yourself down the road.
If you have a timber floor that's not particularly attractive or is made from a patchwork of old and new wood, paint makes the perfect disguise. There are plenty of choices - all the colours from Farrow & Ball are available as floor paint and Nordic Style offers an elegant selection, too.
Analyze your existing paint. The first step before determining if a budget paint job will work on your Mustang is to assess the current condition of the paint. In many cases you can prep and paint directly over an existing paint job, but only if it's in solid shape.
You're not looking for perfection here, but you do want to eliminate every shiny spot of paint. When properly scuffed the paint should have a smooth, but dull matte finish.
However, if you put a coat of pure white primer (which has a score of 0) on top of the brown color wall first, this immediately brings your luminosity score down to 4 (8 + 0 = 8/2 = 4, the average). This means you may only need one coat of yellow paint to give you the right hue and saturation. In reality of course, you will always want to do at least 2 coats. But even with a total of 3 coats (primer and paint) you are way ahead of the paint-only option.
And if you are changing colors be sure you and the paint shop are crystal clear on what color they're going to spray. Never just describe the color. You won't get what you want. Guaranteed. If you're not using a factory original color then find out what kind of car the color you want came on. Give the shop a year, model and paint name and then insist on seeing a paint chip. Take the chip outside to see it in the sun light and verify that it's what you want. There's nothing more disappointing then spending all these hours and money only to watch your car come out of the shop the wrong color.
Another satisfactory whitewash can be made by diluting a moderately heavy cold lime paste (about 33 lbs. of hydrated lime and 8 gallons of water) with 5 gallons of skim-milk.