First: document, then stabilize
Note what you see and when it started, and limit further damage wherever that's safe.
Second: look at the whole property
What's visible is only part of it -- a solid plan also covers water entry, humidity, material condition, containment, and checking the work afterward.
Third: get the scope in writing
Preparation, protective measures, materials, access, permits, testing, cleanup, finish restoration, exclusions, and change-order terms should all be spelled out.
Fourth: line up the bids
Confirm credentials and compare the logic behind each proposal, not just its total.
Fifth: verify closeout
Testing, cleanup, documentation, warranties, and any remaining upkeep should all be confirmed before calling it done.