At the service desk you may be handed a work order and asked for a signature. That paper can change who pays for what, and it is often the first document in the repair that gets read in a hurry. Treat it as a second agreement and read it line by line before the keys leave your hand.
What the work order is for
The work order records what the shop found, what it plans to do, and what it expects the bill to look like. Depending on the arrangement, it may also record whether the shop is asking a provider to approve the work. Read whether the document is an estimate, an authorization, or a repair order. Each carries a different weight.
Read the lines in order
Start with the customer details and the vehicle identifiers, then the stated concern, then the diagnosis, then the planned labor and parts. Look for any line that says the work is covered, any line that says it is not, and any line that is simply blank. Blank lines tend to become disputes later.
Watch for the signature that starts the work
Many shops will begin work once a signature is on file. Ask whether signing authorizes the work, authorizes only the diagnosis, or simply acknowledges that you received the estimate. If the answer is unclear, ask the service writer to write the answer on the document before you sign.
Keep the copy that matches the car
Ask for a copy of the signed work order before you leave, and check that the mileage, the concern, and the vehicle details match what you described. When the car is picked up, compare the final invoice to the signed version. Any difference in the parts list or the labor description is a question to raise before you pay. Keep both papers together so the trail is complete.