Picking a roofing contractor looks like no big deal, but the fact is your roof is the most important component of your home, not to mention the most expensive to replace. Your roof is what shields your home from not only rain, but blistering sunlight, hail, and all types of weather. A good roof system will not only keep you dry but may also significantly lower your heating and air conditioning costs. A roof is not just a lot of shingles nailed on to plywood, it is a system with many components such as roofing felt, pipe boots, drip edge, leak barriers, and flashing. A well applied roofing system should last 30 years or more so do not just go with the cheapest bidder.
The first thing I do is research the company and I do this on my own. It is easy for sales people to just lie about things like that. I want to find out if my roofer is local in case there is a problem with the roof after the job is over. It is very important to have someone who is able to service your area in an emergency.
Secondly, I never ever give a contractor money upfront. All horror stories start with, "I wrote him a check and he was supposed to start the next day". Do not give them any money until the job has begun and then only half. A solid company does not need that money to begin.
Also it is a good idea to get everything in writing. Many people are afraid to enter into a contract but the contract is to protect both the homeowner and the contractor. Many unexpected situations can march through out the project, if it's in writing there will be no question about who is financially responsible for what.
The material used should be of the highest quality, many contractors will save money here. Verify the material is what is specified on the contract.
And lastly, the contractors general attitude should be good. Remember, you will have to deal with this person on a daily basis while undertaking the replacement of your roof.
Do not take your next roofing project lightly. A good roof will add fabulous curve attractive to your home and provide you with long-lasting protection. If you've been burned before you probably already know all of this but this is just a little guidance for new home owners. Hope it is helpful.