10 Things

Do

ONLY hire a contractor who is Licensed, bonded, insured and has worker's compensation.
Meet with other contractors to make sure you are choosing the right one for your needs.
Make sure when comparing contractors that their bids are all the same (equipment, finishes, etc.) this can avoid costly change orders.
Make sure all items you agreed upon with your contractor is included in the contract. READ your contract thoroughly and understand it before your sign.
Ask how long your warranty is for and what is covered.
Collect lien waivers for your records.

Do not hire an unlicensed, uninsured, non-bonded, contractor.
Do not sign anything unless you understand it and agree to the terms and conditions.
Do not make side agreements with subcontractors. This will VOID your warranty. Always consult the general contractor before making any changes to the drawings.
Do not make final payment until your project is completely finished.