Record starting mileage before starting the vehicle and driving to this work.
General rule: If traveling less than 40 miles in one day for this work, you can deduct miles between work locations. if traveling more than that, you can deduct miles from home to and between work locations and back to home. If you fit in personal, non-deductible stops on your route, you do not include those. At this point, someone else needs to comment on whether stopping for necessary food, beverage, and restroom visits are included in route mileage. [And, they should let us know whether any food and beverage on a 40-pus mile route is deductible...]
Hello. Do you track the mileage to a mystery shop and the mileage home at the end of the day?
Things are not to be judged good or bad merely because the public think so. - Tacitus