Using analytics to improve onboarding

Thinking of your onboarding experience as a funnel and using analytics to measure the biggest drop-offs is a useful way to find opportunities for improvement.
Building a funnel means going through your onboarding experience and identifying every touchpoint that you need to track.
The first thing that happens when you do this is you realise you need a destination.
A funnel (in the marketing sense) always leads to some kind of sale. If someone’s paid for your product then what is the point-of-sale equivalent in an onboarding experience?
I doubt there are any right answers here. 

When I sit down with a product and map out the onboarding flow I use the core action as an endpoint to work from.
Your core action is the thing people do in your product that helps them deal with the problem they signed up to solve. 
Rather than working my way into a product, I try and find where the product solves the person’s problem and then work backwards to the sign-up screen from there.
This gives me all the touchpoints someone must go through to solve their problem with the product. 
Investing in analytics and building an onboarding funnel won’t fix the problem but it will show you where your biggest leaks are.