Start by addressing basic questions. What do you want? More living space? An extra bedroom and bathroom? An update for tired old rooms? A new layout to correct dysfunctional floor plans? Will you use the remodeled or new space enough to justify the cost?

Get design help, and put together a serious plan. Architects, house designers, and kitchen and bath designers can convert your ideas and wish lists into a detailed plan with a rough budget.

Vet potential contractors. Hiring a contractor who can turn ideas into reality—as painlessly as possible and at a fair price—is the most important step. Start by consulting customer reviews here at Checkbook.org. Make a list of prospective contractors, and ask them and their past customers questions like: Does the company do the kind of work you have in mind, follow plans, and get work done when promised? Does it help you find low-cost solutions and stick to agreed-upon prices? Does it solve problems promptly? Do workers communicate effectively? Does it limit disruption to your daily life? Are the results as professional and attractive as expected? Is it flexible enough to make changes for a reasonable price if you change your mind?

Interview candidates carefully. Meet with at least three (but preferably four or five) candidates, and go over your plan in detail, asking pointed questions about their experience and credentials, and pointing out potential problems—from your perspective and the contractor’s. Yours will be a close relationship, so imagine what it would be like to work with this person for weeks or even months. Afterward, check out key credentials, including references, licensure, insurance, and complaint history.

Get several proposals and bids. Checkbook’s undercover shoppers found a wide range of pricing for different remodeling projects: from $173,000 to $302,000 for one job and from $26,000 to $61,000 for another. Moral: Get multiple fixed-price bids. Also, don’t assume that there’s any relationship between price and quality. Many contractors do great work at low prices.

Carefully evaluate proposals. Look for detailed pricing, reasonable payment schedules, and flexible terms that accommodate inevitable changes.

Do the deal. Once you’ve chosen a contractor, get a formal contract covering everything from payment terms and deadlines to who does the work and warranties.

Remain vigilant. There’s much you can do to help your project run smoothly. Communicate with your project manager every day. Deal promptly with surprises. If work isn’t done to your satisfaction, don’t pay until the contractor makes it right.