Picking exterior house paint colors is a lot different than picking a color for a shirt or a car. It may help to drive around to observe colors that other homeowners have combined on homes that are of similar size and design as yours. There are also online resources that provide homeowners with the ability to create virtual makeovers of their home by combining colors together through their software programs as well.
Good contracts include descriptions of prep work and repairs; paint specs by brand name, type, color and product number; the number of coats; and a full description of the work, including frequently omitted items such as cabinet interiors and shutters. Minimize delays by specifying that, weather permitting, work will be continuous. Get a payment schedule that minimizes the down payment — the more payment you can withhold until the end, the more leverage you'll have to get the job done well and per your specifications. Insist that contractors provide proof that they carry both general liability and workers' compensation coverage.
I used to work at Sherwin Williams. The best thing to do is specify that you will purchase your own paint. If the painter objects strenuously, he was plaanning on making money in the ways this article outlines. You might pay a few dollars more for paint, but you will have control of the quality of what goes on your walls. Never skimp on paint quality.