In Reports › Payment, you can see a break down of what payment methods are used the most as well as the average size of payments in a given month, and payments broken down by contacts. Filter ‘Payer Totals’ to see who your top clients are. You can use the side filters to specify the time period, brand, job type, job source, and payment method.

You can find the Booking Trends by Payment Type Report in the Reports sidebar menu of your account.  Note that in order to view the Reports section, you must be an administrator user.