This document outlines 12 common mistakes or "sins" that can doom startups. It lists assuming you know what customers want without validating, focusing on launch dates over product-market fit, prematurely scaling the company before proving success, writing rigid business plans that do not allow for testing and learning, hiring co-founders based only on resumes rather than fit, prioritizing traditional job titles over startup needs, managing by constant crisis rather than planning, basing the company around an exit strategy rather than sustainable growth, not accepting that success takes years, and emphasizing execution over testing ideas and iterating as the top mistakes according to the source and the author's own experience.

1. Assuming you know
what customer wants
The “I know what
features to build” flaw
Focusing on
the launch date
Executing on a sales
and marketing plan
Prematurely scaling your
company based on a
presumption of success
Writing a business
plan that doesn’t
allow for trial and error
Having Co-founders
based on Resumes
HIRED
Confusing traditional
job titles with a
start up needs
Management by crisis,
which leads to
death spiral
Building a company
on exit plan
Not believing overnight
success takes few years
Emphasizing execution
instead of testing,
learning and iteration
NO TRIAL
ALLOWED
9 Deadliest Start-up Sins
by Steve Blank
3 more from our own experiences