Exterior paint averages $25-$40 a gallon, and a 3,000-square-foot home takes 15 or more gallons of paint, or $375-$600 just for the paint. However, really premium paint can cost $50-$100 a gallon, or $750-$1,500 for that large home. Doing it yourself also requires renting a pressure washer or sprayer for $50-$100 a day; extra-long ladders or scaffolding at $20-$75 daily; and a power sprayer for $50-$100 daily, plus masking tape, drop cloths and other supplies. However, it's possible to paint a large, two-story house for materials-only costs of $400-$600.
You can expect to pay between $700 to $3,000 to paint wood siding. You’ll end up spending $1 to $3 per square foot, but typically you’ll find this material is cheaper than brick or vinyl. Wood requires some type of sealant, be it paint, stain or oil. Lumber takes well to a wide variety of coverings giving you endless options for modern, contemporary or classic looks. Some things to consider when choosing wood:

You might pay an additional $1 to $5 per square foot for optional repairs and updates. Consider having your molding, trim and baseboards checked while you have a professional in your home. This might be a good time to upgrade or repair any cracks, warps or other issues. Pros can usually touch up or replace these items for an affordable rate, and they may even package such fixups with your project.
After you have done the multiplication, subtract about 40 sq feet per window, and about 60 sq feet per door. Divide by 400 (interior paint covers 400 sq feet per gallon). The number that remains, is how many gallons you will need. If doing multiple wall colors, then you should do this process for each room (or sets of rooms) with a particular color. 
Test different paint swatches. The last thing you want to do is paint a whole room and then decide you despise the color (yes, it happens!). Try out different paint colors on the surface before choosing the paint that you want. Buying sample sizes will help you save money. The caveat: paint color samples are not real paint, so if you try to finish or touch up a project with samples, the paint will fade.

Premium Plus Interior Ceiling Paint 1 gal. features Premium Plus Interior Ceiling Paint 1 gal. features a durable, acrylic-latex formula that is specifically designed for use on previously painted or primed interior ceilings. This spatter resistant formula minimizes glare and provides a mildew-resistant finish. This formula also maintains the original acoustical ceiling properties.  More + Product Details Close
Priming - $30–$40/hour for labor. Many of the materials above need to be primed, but not all do. If you’re changing paint colors from dark to light or light to dark, use a color similar to the top coat. That way you’re less likely to need extra coats over the standard two. Prime with a flat or eggshell paint. You can ask your paint store to add tint to the primer to match it with the top coat color. Hammer in exposed nails and spray them with a metal primer to prevent rust.
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:
Following the same process as the primer, cut in the walls with your chosen paint. For best results, paint one wall at a time. This makes it easier to spread the paint while it’s still wet. Work from top to bottom, rolling the paint in V or W-shaped strokes. Before applying a second coat, wait two to four hours. Then proceed with the same process used for the first coat.

Prep work should include removing all loose paint, either with a pressure washer or by scraping; removing any trace of mildew using bleach and water or a commercial solution, and sealing or covering dark stains; caulking all seams, corners and around windows or trim; applying epoxy filler to repair serious woodwork problems; covering dark stains; sanding all rough surfaces, and priming the bare wood with a bonding primer.

Latex paint refers to water-based paint, the most popular and environmentally friendly paint. Since latex paints provide great color retention, they’re ideal for exterior walls that face a lot of weathering. Latex paints are also a good option for interior walls that are subjected to a lot of moisture, such as bathrooms and laundry rooms. Additionally, latex paints dry faster than oil-based alternatives and produce fewer odors.
Whether you decide to do the preparation work yourself or have a professional do it as part of your project, proper preparation makes all the difference in creating a smooth and lasting finish. Do it correctly the first time or you’ll quickly end up spending more to fix peeling and chipping paint. Follow this process before starting on your home's exterior. Keep in mind that the process may vary based on your siding materials: