According to Craftsman National Estimator, "High time difficulty factors for surface preparation and painting. Painting takes longer when heights exceed 8' above the floor. Productivity is lower when an application requires a roller pole or wand on a spray gun or when work is done from a ladder or scaffold. When painting above 8', apply the following factors:
The Coordinator. This person will care for the needs of the rest of the workforce, fetch drinks, make sandwiches, make runs to the store for last-minute needs, cook (or arrange) lunch and dinner, make phone calls, get directions, wash brushes, etc. Don't underestimate the need for this key person! When not gainfully employed, he or she can do some rolling.

Paper/poly drop cloths: $2 to $6 for 9x12-feet. The best of both paper and plastic, these cloths are low-cost and disposable. They absorb paint drips while providing more protection for what's underneath. They also provide some protection from slipping. Plus, you can cut paper/poly drop cloths to fit the space. But, like paper, paper/poly drop cloths can rip more easily than plastic or canvas drop cloths.
While many professionals use paint sprayers, they can leave drips and uneven coatings in the hands of an inexperienced user. If you’re set on DIY house painting but don’t have much practice, you may want to stick to rollers and brushes. Brushes are great for edges and smaller areas, while rollers can be used to paint large and long surfaces like siding and trim.
The Ceiling. For ceilings, flat is recommended, except semigloss or satin should be used in bathrooms with showers/tubs. Some customers opt to go with a different finish for ceilings in general, to create a specific design look, i.e. high gloss ceilings on dining room tray ceiling to make a statement, or eggshell ceilings throughout to look modern and make a statement. 
Compare offers. The painter offering the lowest rate may not always be the best painter for the job. Indeed, the total cost isn't the only factor to consider when choosing between multiple bids. You'll want to look at contracts side by side to ensure you're making an apples-to-apples comparison. Are the same materials being used? Are the same services included? Does the painter provide a warranty?
When determining the total cost of a home’s exterior project, you’ll want to include things like the trim, a garage, foundation, windows and doors. All work is calculated by square footage and sometimes by the linear foot, such as in the case of trim. Your contractor will give you a price for the entire project unless you specifically ask for each item separately.