Here is a Google Sheets template for keeping track of your jobs, how much you're making, whether you've been paid yet, etc. You can obviously edit and tailor it to your needs, but this is super helpful to do for the following reasons:
Lets you keep track of the projects you were in and which roles you played. You can even use it to keep track of release dates so you know when your projects are expected to come out.
Gives you a client list (in case some clients forget to send you 1099s for taxes, or to help you follow up in the future with clients you haven't heard from in a while)
Lets you easily keep track of how much you're making per month or per year-to-date (you can highlight the "total amount" column and it will automatically add up the sum for you of all the cells selected to let you know how much you made that period!)
Lets you keep track of whether or not you've been paid yet for jobs you did. For instance, if a few months go by and you see you still haven't been paid for "Example Game", it lets you know to follow up with "John Doe" regarding payment. I like to highlight once I receive payment for a job so that I know it was paid, in addition to marking the "Y" in the paid column. You can see this in action with one of the examples provided, but do what works for you!
I've included a few sample/filler "jobs" on there so you can see how the spreadsheet works. You can go ahead and delete these once you're ready to put in your own info, of course.