I keep a spreadsheet of commissions, inside various aff programs i try to track as much as i can with as much granualarity as possible.
I measure success by monthly commissions and the trend (growth/drop) in sign-ups/depositors.
I’ve found that there were people above and below me in earnings in the industry when i made $300 a month and when i made, a lot more. So it’s better to measure against your own plans, needs or dreams than against other webmasters.