Even in this Internet age, personal references are far more useful than online reviews, though you should certainly read those, too, as well as seeking referrals from online services such as AngiesList.com, HomeAdvisor.com, Google and Yelp. When choosing a contractor, nothing is more important than references. Ask friends, relatives and co-workers for references. People in your neighborhood who have done similar projects are your best sources.

If you know people in the building trades, ask them, too. Employees of local hardware stores may also be able to provide referrals.Go to see the work if you can, and ask the homeowner detailed questions about what it was like to work with the contractor. Consider interviewing subcontractors as additional references and asking if the contractor treats them well and pays on time .

General contractors and most subcontractors should be licensed, although the procedure varies by state and municipality. Check the disciplinary boards, Better Business Bureau and local court records for problems. Ask the contractor for a copy of his license and copies of the licenses of the major subcontractors who will work on the job.

Obtain a list of references from previous clients. Then call those previous clients and ask detailed questions: Were they satisfied with the work? Did the project go over budget and why? Did the contractor show up on time? Did he clean the job site when he left?

“If it’s a really large job … you should go a little bit further to verify that they’ve done that kind of work,” Contant says. This includes asking additional questions, consulting more references and doing an in-person visit to a past job. Someone who did a good job tiling your neighbor’s bathroom isn’t necessarily the right person to build an addition to your home. You want to find a company that routinely does the kind of project you want done.