The GC should provide you with a contract. Here are the things I would recommend looking for in that contract.
1. Scope of Work: Clearly define the tasks and responsibilities the contractor will undertake. I can't tell you how many times I have heard, "That was never in the bid." Put it in writing so there is no miscommunication.
2. Payment Terms: Outline how and when payments will be made. There will be an initial deposit, progress payments tied to milestones, and a final payment upon project completion and satisfactory inspection.
3. Project Timeline: Specify the start and completion dates, including any deadlines for specific milestones. Include clauses for delays and how they will be managed.
4. Change Orders: Detail the process for handling any changes to the scope of work, including how they will be documented, approved, and the impact on the timeline and budget. This is a big one! Change orders will most likely happen!
5. Permits: Clarify who is responsible for obtaining necessary permits! Contractors should do this, but to be safe, I would outline it in the contract.
6. Termination Clause: If things don't work out, define the circumstances under which either party can terminate the contract.
7. Lien Waivers: Require the contractor to provide lien waivers from themselves and all subcontractors to prevent any future claims against the property.