Summary: This is part IV of four articles describing the three-step principle for easy shaping of the breast in reconstructive and aesthetic breast surgery. This article may seem overdue because aesthetic corrections are routinely performed, frequently written about, and easier to execute, as no prior ablative surgery or radiotherapy has damaged the gland. Nevertheless, a number of difficult aesthetic breast surgery cases can present themselves that might be more challenging to correct (e.g., tubular breast deformities or corrections after failed aesthetic breast surgery). By understanding the three main anatomical features of a breast—the footprint, the conus, and the skin envelope—and how they interact, as explained in part I, one is able not only to analyze the deformities of each individual problematic breast but also to teach others and to execute a specific surgical strategy on how to obtain reproducible aesthetically pleasing results. The three-step principle will be applied and explained for breast augmentation, reduction, mastopexy, and tubular breast deformity.