For a job of almost any size over a few hundred dollars, it is usually important to have a written contract. Here are some factors to consider as you get ready to hire your contractor:
Contract terms
Most states have standard contract language that your contractor will be using for a simple contract between you and them. Read the contract carefully to make sure everything looks in order. If you have any questions, ask the contractor for clarification or your lawyer for guidance.
Permits
Make sure your contractor knows which permits they will need for the work you need done and then make sure they get any and all permits for your work. Do not under any circumstances let them talk you into skipping the permit step. There will be significant liability for you if you do this, especially when you decide to sell your house.