If a firm wants you to run on 260-mile round-trip commercial inspection with a 100-page report and loads of photos, make absolutely sure that both parties commit the agreement to a writing that specifies the details of the job and what is required by both parties.
What is fee? Will mileage be paid? At what rate? What is the due date? What are the deliverables? When will payment be made? Write out the details of the agreement.
Verbal communications often get garbled. Put the agreement in a writing to reduce the chance of garbled communications on expectations. Get it in WRITING!