1. Look, and don't make it worse
Note what you're seeing, hold off on anything that could cause more damage, and pull together whatever history you have on the home.
2. Look at the house and site together
How the sheathing, the water-resistive barrier, window flashing, and trim details all tie together decides how long the job actually lasts, not which brand of siding gets chosen.
3. Get it in writing
Preparation, protection, materials, access, permits, testing, cleanup, finish restoration, exclusions, and change orders should all be spelled out before work starts.
4. Weigh the proposals
Check credentials, then compare the reasoning behind each bid and where its boundaries sit, not just the bottom line.
5. Walk the finished job
Testing, cleanup, documentation, warranty paperwork, and any ongoing maintenance should all be confirmed at closeout.