The document discusses three common mistakes that clients make with user experience (UX): 1) Not investing enough time, money, and energy into planning upfront with activities like research and prototyping; 2) Spending too much focus on visual design and "look and feel" rather than content, copywriting, and lead nurturing strategy; 3) Thinking that all users enter through the homepage when analytics show many users land on interior pages. The document provides examples and resources for addressing each mistake by shifting focus to recommended areas like planning, content strategy, analytics, and designing all website pages.