I like Just Enough Research by Erika Hall.
Beyond that I think behavioral science is where it's at. The rest is cruft, business stuff that might become important, but what a startup needs is empathy, if not curiosity for human behavior. I recommend Designing for Behavior Change: Applying Psychology and Behavioral Economics. Nir Eyal's weekly newsletter is great, don't take his stuff seriously, just read the things he links to broaden your horizon. Never forget to think for yourself though, nobody has the entire picture, so be sceptical, take the good parts, leave the rest. Experiment. Be a little scientist yourself. A responsible one though. We have enough baddies out there already.
I have also found Peter Thiel’s book Zero To One to be full of actionable insights and recommendations.
Finally, Eric Ries’s The Lean Startup is the bible of iterating fast and finding product-market fit before you invest in a product no one wants (#1 most common way to fail).
Just my 2 cents.
(Disclaimer: we are not funded by YC)
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