Also prime the ends of adjoining boards. This step pays off by slowing the moisture penetration that can lead to peeling at the joints. If the new siding is redwood or cedar, buy a special “stainblocking” primer. Both of these woods contain natural chemicals (tannins) that can bleed through paint, causing brownish stains. A stain-blocking primer will seal in the tannins.
The article and comments were great information to have before deciding how to go about getting a painting job done. I think the important point is that there are several key choices (who to do the work; color, sheen, quality, of paint; how many coats; amount of prep/repairs to be done and by whom, how long the job will take, provisions for changes, how detailed the contract needs to be; advanced deposit/progress payments/final payment; final inspection, etc.) that need to be made and it requires advanced research and planning in order to become well enough informed to make the right choices. Then it requires spending sufficient time to check materials and inspect the quality of the work while it is on-going, raher than waiting to do it all at the end. President Reagan's philosophy of "Trust, but verify." applies.
Here is where this affects you as a consumer. You select a painter with a contract that says 2 coats, $500 down. You give the company the deposit and pick your colors a couple of days before the project starts. The painter goes to the store with your colors and figures out they are deep base. He (or she) not only needs to charge you more for the paint, but he also needs to charge you for a dark gray primer coat. Ninety nine percent of the time that primer coat is going to be really, really expensive since you already gave a deposit.
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.