1. Start by documenting, not diagnosing
Note what's showing up, take safe steps to keep it from getting worse, and gather any relevant history on the home.
2. Evaluate the house and site
How the unit gets installed, the flashing detail, the sill's condition, frame material, glazing package, trim finish, and which way the wall faces the sun all weigh as heavily as which window you pick.
3. Get the scope in writing
Spell out prep work, what gets protected, materials used, site access, permitting, testing, cleanup, finish restoration, what's excluded, and how changes get priced.
4. Weigh proposals, not just totals
Check credentials, then compare how each provider explains their approach and where their scope stops — the bottom-line number is the least useful part of the comparison.
5. Close the loop before signing off
Confirm that testing was done, the site was cleaned up, paperwork was handed over, warranty terms are documented, and you know what maintenance is still on you.