I was impressed with this presentation from iStock for us. Although they ignore illustrations, it's still useful. https://www.brighttalk.com/community/customer-experience/webcast/10189/150537?utm_medium=web&utm_source=brighttalk-portal&utm_campaign=community-live-recorded

I thought it was incredibly ironic that the video immediately below this video was titled (and no, I am not making this up): How to Win Back Fickle Customers. (Needless to say, that one was not created by iStock/Getty -- but maybe someone there will watch it).