You should always be sure to get detailed quotes from at least two to three different contractors. Once you have three quotes sit down and compare the estimates paying special attention to the materials used and the labor costs. Just as important, be sure to talk to people who have previously used these contractors. Ask if they had any complaints, if they cleaned up nicely, if they finished on time, kept to the contract etc. Any roofing business relies on referrals, so find out what you can, and choose what suits you best.