A tremendous read for any entrepreneur from Tren Griffin's blog. As Reid Hoffman notes, “Product/market fit requires you to figure out the earliest tells.” Using an analogy to poker is appropriate since the process of finding PMF fit is an art rather than a science.

“You can always feel when product/market fit isn’t happening. The customers aren’t quite getting value out of the product, word of mouth isn’t spreading, usage isn’t growing that fast, press reviews are kind of ‘blah’, the sales cycle takes too long, and lots of deals never close.