When painting a carpeted room, keep in mind that paint will soak through drop cloths. This is especially true of the cheaper, lightweight cloths. It helps to tape masking paper to all of the base boards before laying the drop cloths. Tuck the edges of the cloth under the paper--this will help keep it clean. You might want to invest in a hand-held masking machine--they make the job go much faster. Even after taking these precautions make sure to clean big drops or spills before they soak through and before you step on them!
To solidify this response, we have been in business for over 30 years as a painting contractor. We didn't just paint a couple of houses 25 or 30 years ago, we paint approximately 900-1000 painting jobs per year and operate with 40 professional painters doing commercial, residential and industrial painting. This article on behalf of Angie's List is totally asinine! I was under the impression Angie's List was only carrying "legitimate" contractors with established reputations. This article written is primarily referring to bottom feeding, one man band operations, trying to hustle for a paycheck.
Prime. Dark colors, stains (once sealed), and previously unpainted surfaces (drywall, spackle, etc.) will need a primer coat, usually white. NOTE: most paint stores & home improvement centers will now tint primer (at no charge) to match fairly close to the color of the finished coat, that way two coats of primer need not be applied. Although not all surfaces need a prime coat, skip this step at your peril! Dark colors will likely show through the first -- or even the first couple-- topcoats of paint. Sealants and unpainted surfaces like spackle patches will absorb or repel moisture in a topcoat at a different level than the areas surrounding them. Applying a good primer coat will help even out these differences. Primer equalizes a wall to a uniform surface. It's like erasing a canvas before drawing a new picture. Although some will argue the point, you generally don't need to spend a great deal on primer or buy special primer. A cheap, 5 gallon (18.9 L) bucket of plain, flat white paint will usually do the trick and cover a large area. Give your primer at least 24 hours to dry (follow its instructions) before applying a topcoat.
Sorry it is difficult to trust almost anyone in the trades. It is easier to do the work myself and not deal with strangers in and around my house. When I have to hire someone I tell them up front that I'll be checking every detail, pay extra to purchase the materials myself, and if they don't want the job - well good! I always fine someone who will work with me as I pay a bonus for that.
Depending on just how dirty the outside of your house is and on the house's size, there are two ways to approach this job. If you live in an average-size house, use a garden hose with a carwash brush attachment to bathe the big areas. For caked-on dirt, use a scrub brush or a sponge and a pail of warm water with a good, strong household detergent in it. Work from the top down, and rinse all areas where you scrubbed with water.