I read a book on Customer Success and spent a lot of time on one of the co-authors (Lincoln Murphy) website, and came to realize that the role of customer success in an organization, but especially software as a service organizations, should be the first hire made. Something I have completely overlooked to date. It took me awhile to understand the flow of the role and what it can achieve, but I think it boils down to this:
Know who your ideal customer is. Define the profile. Update it constantly. It should be changing.
Know what they want, what their desired outcome is, their job to be done, not your solution, their problem that they want solved.
Map the journey they will take through your company to reach their desired outcome.
Along the map mark the success milestones that you and they want to achieve.
Determine where you lose them. Where are the gaps in your journey that they sometimes fail to cross.
Figure out how to bridge those gaps. An intervention. Self serve documentation. A service you sell them. A third party solution. Whatever it takes, bridge those gaps.
Segment your customers into success vectors. A success vector is a grouping of customers by the lifetime value that they have to your company. Could be as simple as free user, person, business and enterprise, whatever grouping works for you and that has enough statistical / relationship significance to call that collation of customers a group with a more or less similar lifetime value.
Just like bridging the gap in your journey figure out how to ascend customers up through your success vectors. How to increase the size of the groupings at the top end of your ladder.
Measure the success of the role by account churn (should be less than 1% per month) and revenue churn (should be 0% or negative). How can you have 0 or less revenue churn? By increasing the lifetime value of existing customers from account management sales such that those sales meet or exceed any revenue churn that you might be experiencing. How? Customer success should be generating highly qualified leads for your self serve (automated purchasing and checkout) and full serve (Account Managers) to sell back to the existing customer base. Added bonus, measure the number of referrals and testimonials that you get from them.