I'm old, my hands don't work right because of an accident. So handwriting isn't gonna happen. I don't have notepads or spread sheets on paper. I have 6 folders in my filing cabinet, one per month. Most MSC's require you to keep your receipts and proof of shops for 6 months. I put the current month's folder in front at the beginning of the month, empty the contents of the folder from 6 months prior, then put all of my receipts in the folder when I get home in the evening (or whenever). I use google calendar on my desktop, sync'd with my phone, to keep track of the jobs, the days I'm doing them, and what MSC I'm doing the jobs for. When you're scheduling on the calendar remember to leave spaces for driving time, and breaks for meals if they aren't jobs you're doing on your route.
For the shops that you need to track time and get names and such, there is a cool app called ShopIt. To someone glancing over your shoulder it looks like a text message window. You can just tap the screen to mark a time, and you can note the answer to questions, or names of associates, and descriptions if the shops call for such things. And when your shop is done you can save it or you can delete it. I found that it's easier for me to delete the notes once I've finished and submitted the shop as long as I keep my receipts and proofs.
On my desktop computer I set up a Work Picture file, with sub folders for each month, and inside the month folder, a file for each day that I go out and shop. I transfer all of the pictures from my shops to the date files, and on days that I do a LOT of shops, I make sub folders in the day folder for each Job ID#. If I only do one or two shops in any given day I just put the pictures from that day into the date folder because I'm lazy. And, at the end of 6 months, I delete the month, and make a new folder for the current month.
I'm kinda weird about wasting paper, so if there is a way to print ONE page, instead of 2 or 4 or more, I will. As an example: I do store audits for one company, I print out the questionnaire ONE time, printing on both sides of the page, and I print out as many signature pages as I need for the audits I've scheduled. I answer the questions online on my tablet while I'm in the store, so I only need the questionnaire as a reference.
Usually during the first week of the new month I don't do a lot of work, so I take care of my bookkeeping, and file disposal and such then. Most of the MSC's have some kind of Pay Statement that you can access, except Sassie companies, those you have to find your completed shops and check them individually, each shop will have what you were paid, and most MSC's show the date you were paid for the job. Sassie platform MSC's are always more work, and more non-paid work for keeping track of your work. I'm not going to say, "but it's worth it."