What is a go-to-market strategy, and what goes into it?
It's the written decision on who to sell to, what to promise, at what price and through which channels, with the numbers that tell you whether it's working. It isn't a document to hand over; it's a plan you change every week.
The numbers to watch
Two rules of thumb common in SaaS, from David Skok's metrics: a customer's lifetime value (LTV) should be more than three times what it costs to acquire them (CAC), and that cost should be recovered in under twelve months. They're heuristics, not laws: they help you tell early which channel to keep.