Definitely a sizable deposit. No one ghosts a deposit.

Unless the customer is a regular (known shop), we take a deposit from everyone. Otherwise, they'll continue shopping after they book you.

We require 50% deposit at time of booking from the quote. Also have a disclaimer on the quote stating that their are often many variables and anything not stated in the quote is billed at T&M rates.and they sign that this is understood. Eliminates a lot of questions on completion and get paid for all the extras

Good rule, never let any work leave the shop that you haven't been compensated for. It saves so much in hard feelings.
And a companion rule; People need incentives.
Rich

Like Patrick Ball said, 50% deposit and disclaimer on contract signed before ordering any materials or scheduling. I learned the hard way starting out and got screwed out of 8k. It was subcontract work for another shop I thought would never get over on me. Well that was an 8k mistake. Next day I had a lawyer write up contract.

Same thing here. 50% deposit to cover materials. Sometimes we may ask the customer to prepay the entire job. Reason being if they are dropping off something with no resale value and the job is completed and they never show up again, you don't get paid for your labor.

Some customers complain that their mechanic never asks for any deposit. I just help them see that when you drop off an entire car for work they don't ask for a deposit because they'll just sell your car if they don't hear back from you. It's called a mechanics lien.