A can of paint, a brush, some rags, a ladder and you (and some friends if you’re lucky).

Painting projects can turn you into a home-improvement artist, dramatically transforming a room or providing a complete exterior makeover for more creativity than cash. You can DIY if your gables or eaves aren’t too high and your patience isn’t too thin. Before taking the painting plunge, though, consider the following:

Inside there are solid floors, reachable ceilings and uniformly bright working light. Outside, uneven ground makes it difficult to set ladders and reach roof overhangs. Nature isn’t your friend here either: Morning dew can cause paint adhesion problems, and storms can ruin still-wet paint.

Applying one coat in one room is a reasonable DIY Saturday project (especially if you have help and beer). If you multiply the time spent moving furniture, prepping walls and sanding old trim by the number of rooms in the house, you might want to hire folks in painter’s overalls. It’s the same outside. You can probably tackle one shady garage wall that needs a little scraping and sanding plus a coat of paint, but covering all surfaces of the house is usually best left to a pro.

Painting one story might be within the scope of a DIYer. Two stories means extension ladders and scaffolding, probably contractor territory.

If a remodeling contractor leaves smoothly finished drywall, that eliminates prep work, and the painting can begin. Where walls or siding need a lot of scraping, spackling and sanding, the same-sized project can take twice as long.

Repainting with a similar color rarely requires more than spot priming and one finish coat. Dramatically changing the color usually requires at least two coats, doubles the painting work and generally necessitates extra time for drying.

A roller makes quick work of unobstructed walls. Rooms with wide baseboards, elaborate window casings and cornice molding at the ceiling demand more time and effort. Ample trim means a lot of brushwork — even more so if the job includes cabinets and shelves — and edges into the realm of professionals.

Homes built before 1978 could have now-banned lead paint, and you might need to employ some special work to minimize possible exposure to toxic materials. This might make you want to go pro. Good contractors will take steps to protect your family and their workers.

Take a look at painting projects you’ve tackled in the past. Is the trim as smooth as you would like it to be on the new project? Are the walls uniform and free of lap marks? If you want results that might be difficult and time-consuming to achieve by yourself, hire a good contractor.

To help you find a pro who will do the job right, use Checkbook’s ratings of local painters. Until Oct. 5, Checkbook is offering free access to its ratings of area painters to Star Tribune readers via Checkbook.org/StarTribune/Painters. Have several reputable contractors inspect the job and provide proposals. You’ll likely find huge price differences.

A Checkbook undercover shopper solicited bids for two separate jobs: (1) Re-caulk and repaint all exterior wood trim, including 27 windows, on a two-story, 3,000-square-foot home; and (2) Repaint the walls, ceiling and trim for a foyer, hallway, two bathrooms, two stairwells and three bedrooms. Prices include paint and supplies.

For the exterior work, prices ranged from $1,830 to $6,800, a difference of $4,970. For the interior work, prices ranged from $1,175 to $4,780, a difference of $3,605. Don’t assume low prices signify lousy work: Checkbook found companies that perform top-quality work are just as likely to quote low prices as companies that do shoddy jobs.

Ask companies to include all details in writing. Although that sounds simple enough, too many contractors submit offers such as “paint house for $3,000.” A friendly contractor might offer a reassuring handshake and promise the crew will take care of all the details like starting on time, working every day, cleaning up, etc. That’s great, but why not include each point in the proposal?

Good contracts include descriptions of prep work and repairs; paint specs by brand name, type, color and product number (check Consumer Reports’ paint ratings; in its tests, some relatively inexpensive paints performed better than more expensive ones); 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. Set a payment schedule that minimizes the down payment: the more payment you can withhold until the end, the more leverage you’ll have to have the job done well and per your specs. Insist contractors provide proof they carry both general liability and workers’ compensation coverage.

Twin Cities Consumers’ Checkbook magazine and Checkbook.org is a nonprofit organization with a mission to help consumers get the best service and lowest prices. We are supported by consumers and take no money from the service providers we evaluate. You can access Checkbook’s ratings of local housepainters until Oct. 5 at Checkbook.org/StarTribune/painters.