Do you react well when someone tells you "calm down"? While that phrase might be an obvious problem, Cori Pearce of ChurnZero has some other not-so-obvious phrases you should avoid saying to a customer no matter how well-intentioned or deserved.
In the 4th article of his Financial Foundations guide (3rd article here), Tom Lipscomb of The Successful Customer (via Strikedeck) talks about using and understanding various revenue and cost ratios to optimize financial success.
Though traditionally account plans are in the realm of sales, Customer Success can greatly benefit from one to help improve the customer relationship and drive renewals. Daniel Currin of Hubspot has a template you can use to create your customer plans.
Asking the question “what should I look for in a CSM?” is like asking “what kind of person do I need to fill my Sales role?” Any answer other than “it depends” is either naïve or based on a set of assumptions. Dan Steinman of Gainsight has two strategies for how to hire based on the role you see for your CSMs.