In this mixed-methods study, librarians at Kennesaw State University Library System conducted a year-long design research project to create a flexible subject guide "blueprint" for undergraduate students using LibGuides. Methods included a card sorting study with 18 undergraduate students and usability testing with 40 undergraduate students. The study's goals were to identify what content, aesthetic design, organization, and structure students preferred on a subject guide. This paper addresses the current literature on research guides usability, overviews the design and implementation of the study, and highlights practical results that will easily be transferrable to other libraries.