I print at least the first page of my shops. This page gives the name, address, shop date, and fee. I then google the directions on my phone which takes about 1 minute and I annotate the mileage on this page. This is my permanent record. I record the mileage on the vehicle I use on January 1 and December 31. I keep the receipts for all supplies and tools I purchase to do the job. This information allows me to correctly fill out a Schedule C. I feel confident about the accuracy and correctness of the information I submit with my tax returns as it pertains to Mystery Shopping.