When education researchers describe newly developed curricular materials, they typically concentrate on the research base behind their design, and the efficacy of the final products, but do not highlight the initial stages of creating the actual materials. With the aim of providing useful information for faculty engaged in similar projects, we describe here our development of a set of in-class tutorials for advanced undergraduate electrodynamics students, and discuss factors that influenced their initial design and refinement. Among the obstacles to be overcome was the investigation of student difficulties within the short time frame of our project, and devising ways for students to engage in meaningful activities on advanced-level topics within a single 50-minute class period. We argue for a process that leverages faculty experience and classroom observations, and present several guidelines for tutorial development and implementation in upper-division physics classrooms.