Creating or recreating an aesthetically pleasing breast shape in reconstructive and aesthetic breast surgery is an act that most experienced "breast" surgeons will find self-evident. We propose a simple three-step philosophical and hands-on approach that will make it easier for young and unexperienced plastic surgeons to not only analyze the problematic breast but also come up with an easy surgical strategy to create reproducible results.This is Part I of four parts describing the three-step principle being applied in reconstructive and aesthetic breast surgery. Part I explains how to analyze a problematic breast by understanding the three main anatomical features of a breast and how they interact: the footprint, the conus of the breast, and the skin envelope. Part II deals with reconstructions after complete mastectomy and Part III covers reconstruction after breast conservation surgery. Finally, Part IV applies the same principles in the field of aesthetic breast surgery. Throughout these four parts, the three-step principle will be the red line to fall back on to define the problem and to propose a solution.