Please ask to see a copy of the contractor's license and insurance before work is begun.
Ask for and inspect finished projects of local references. Ask for a paid receipt from the material supplier prior to making final payment.
If you want work done by or on specific dates have these details included in the contract.
Make sure you understand all financing and contractual terms and never sign a contract with sections left blank.
Get all details in writing, study them carefully, and ask questions (get answers in writing) before signing anything.
It is customary to pay a portion of the estimate up front to cover materials (make sure these are specified in the contract), to make a second partial payment partway through the job, and then a last payment after the job is done and inspected.
Get any changes to the contract (due to unforseen problems) in writing.
Do not make final payment until the work is completed.
In planning a program to extend the life of your home's roof, you should: have periodic (annual) roof inspections, apply roof coatings before serious roof deterioration occurs, shop for an experienced and reputable roofing expert, and always use a roof coating that is chemically compatible with what is already on the roof carefully following the manufacturer's instructions.