In my experience, a good way to find a reliable contractor is to know a very experienced real estate agent. They usually have a favorite contractor or two for just about everything (after already weeding out tons of them for you) since their clients need them so frequently.
I'll be a naysayer on this advice. Real Estate Agents know contractors who work quick and dirty to get the job done to get the house sold. That does not mean they know 'good' contractors.
Case in point, when I bought my house, an inspection showed that half of the roof was way overdue for new shingles. I wanted to get it done myself and get a credit. My agent advised me against this, because there could be underlying issues. Anyways, the seller fixed the roof via their agents recommendation. Needless to say, the work was ---smurfy--- and I had ridge shingles falling off my roof in no time. The offending realtor is also a neighbor of mine. Needless to say, by the time the situation was sorted out and fixed we had words and are no longer on speaking terms.