With today's recession, you will find many contractors ripping people off. Especially in area's hit by natural ldisasters. But if you know what to look for you can save your self some heartache. Make sure the contractor you are hiring, has the skills and background to work on your project. It is important that they have the proper insurances, and licences also. And what kind of warranty are they going to offer you. Before you sign any contract, ask questions, lots of them.
The best way to protect yourself also is to verify the contractors credentials, before the start of the job. For ac construction or plumbing make sure they are HVAC installers and have their current HVAC license before installing any units in your home.
It is vital that you verify your contractors insurance, because if they cause damage you will be able to protect yourself. Make sure they have the proper liability insurance, this is what will cover for any damage that may occur.
References, references, references I can not say it enough. Always verify them, don't take the contractors word for it, ask for customers phone numbers if available. Or a address you can ride by and see the work they have done.
What type of warranty are they offering. Warranties are the contractors backbone to his business. Long warranties are the best. Be wary of warranties that the contractor is only giving you a year on labor work. Also look for contractors who will match manufacturer warranties on products they are installing.