I really would suggest incorporating the information directly into your shop sheet. When you list a job you have accepted, you probably want columns for:
1) Odometer reading out
2) Odometer reading on return
3) Mileage for this job (this is the second number above minus the first and can be made to be an automatic calculator)
4) Earliest performance date
5) Latest performance date
6) Store or client name
location address
7) MSP you are doing the shop for
8) A column for notes, such as hours for shop, phone# if call ahead, etc.
9) MSP's job number
10) Date you performed the job
11) Date you reported the job
12) Stated fee
13) Bonus promised
14) Reimbursement promised (change to actual reimbursement if you spend less than the maximum amount)
15) Unreimbursed expenses
16) Date paid
17) Amount paid
18) Payment pending
These are the basic pieces of information you need. You may find it useful to add additional columns for scheduler names or email addresses, whether an invoice is required and if/when you submitted it, etc. The core of your information, however, is above.
When you accept a job, immediately you can enter 4-9 above as well as 12-14. I usually copy and paste this information from the website as much as possible so that I KNOW I didn't get it wrong by making a typo.
When I do the job, part of my reporting is my interaction with my spreadsheet. I now can fill in 1 & 2 and if I have put in a formula for 3, that will be calculated for me. I fill in 10 and 11 (sometimes a report is submitted after midnight so the date will be different and some companies will allow reporting the following day anyway). I make any changes to 14 (maximum reimbursement for a dinner shop of $50 was on the sheet but I only spent $48.53 so I will change the $50 to $48.53). 15 is trickier. There are times when you have a flat fee shop but are required to make a purchase. That expense goes in 15. Sometimes you had a reimbursement of $20 but were unable to meet the purchase requirements for less than $23.48--$20 stays in reimbursed, $3.48 goes in 'unreimbursed expense'. Be careful with this column because it is only required expenses where the reimbursement did not cover the costs entirely.
Now my sheet will calculate 18 for me by a formula that adds together 12, 13 and 14 and subtracts out 17. I can make any other notes I need to make in appropriate extra columns to the right. With a new-to-me company I am likely to put in a date by which I expect to see payment. I may note whether payment will be by check, direct deposit or paypay so I don't have to go look it up again. I may note the scheduler or a phone number or a reminder to mail receipts etc.
With my own sheet I assign a job number of my own to every job. Mine run across years so at any time I know how many jobs I have performed. I simply have added a column before 1) to do this and it means I can sort my spreadsheet for any of a number of purposes and still return it to the sequence in which my jobs were performed.
There is not room here to teach you how to use Excel, but suffice it to say that I create a workbook where every month has its own page of the above information. Because my printer is not exclusively for my shopping activities, I charge per page for printing and claim no deduction for paper, ink or the printer itself. I keep track of postage to mail stuff in that is not directly reimbursed (if reimbursed, that amount gets added to the 'reimbursement' column). If I have to fax information in, that is annotated in at an average cost per page for the number of pages. I "freeze" the top panel of my sheet so my column headings show up no matter how far down the list I am for the month. I have running totals for the month in that frozen top panel for mileage, fees, bonuses, reimbursements etc and of course the outstanding payments. When I get paid, I highlight the line that is now paid so when my whole sheet has "turned blue" I know I am fully paid for the month and until that time I can easily spot shops that haven't been paid. When I request a shop I am likely to put the basic information for that shop (4-8 and 12-14) into my sheet and highlight it in yellow so that I know what I have requested and can remember to delete the request if accepted jobs make it no longer interesting (not going to be in that area during the time frame, etc.). If I get the job the yellow highlighting comes off and I finish filling in the data specifics in 8 and 9 as needed. If I cancel my request I just delete the line.
With my sheets I take the totals from the heading areas at the top of the page and feed them through to a recap sheet which shows me each month's activities, the outstanding amounts total and sums everything. I also have an expenses sheet for those things like equipment, cell phone bill and other deductible items that feeds over onto the recap sheet.
My sheets also become a whole tax information and life information thing as I keep track of non shopping appointments, birthdays, etc. because this IS my calendar as well. Medical copays and mileage for doctors' visits and pharmacy runs have a page of their own that breaks them down into the categories I will find on my tax return. A monthly running sheet of all bills to be paid is part of the overall packet and they get highlighted as I set them up to be paid and the highlight removed as they are paid from my checking account. If it is tax deductible, it is documented in my sheets as I go through the year because several times a month I am looking at my bank account on line so can see the inflows and outflows. I go over my credit cards carefully before setting them up to be paid. If it is a mystery shopping expense I don't worry about it because it is on my shop sheet. If it is a farm expense (feed, meds etc.) it gets copied to that page of my workbook while I am reviewing the cards. I keep an auto sheet more for curiosity than use as I take mileage, but the insurance, gas, repairs and maintenance are all copied to there. In other words, my sheets go well beyond the basics because it is a convenient way to keep track of everything. It is the first file opened every morning and the last one closed every night.