Where to set the standard by Sarah Guo is an exhortation to move quickly. The biggest advantage startups have when trying to break into existing markets is the agility that larger, more established companies can not match. This short essay urges you to embrace that advantage, and not worry about high standards scaring people away. High performers embrace high standards.
Excuse me, is there a problem? by Jason Cohen is a great overview of analyzing the market for your potential startup. But the big contribution from this article is a quantitative framework for rating your business idea and classifying it as appropriate for high-growth, VC-funded scale up, a medium-growth bootstrapped business, or just something not worth pursuing.