This guide is intended to help users optimize sample preparation for stimulated emission depletion (STED) nanoscopy, specifically when using the TCS SP8 STED 3X nanoscope from Leica Microsystems. It gives an overview of fluorescent labels used for single color STED imaging and a ranking of their performance. Fluorescent label combinations for dual and triple color STED imaging that minimize cross-talk during detection are recommended. There is a discussion of considerations for immunofluorescence labeling and a detailed protocol to obtain high quality images, with a high signal/noise (S/N) ratio, of interesting structures in a specimen. Important details for sample mounting and substrates that enable optimal imaging, minimizing aberrations and autofluorescence due to the mounting medium, are reviewed. Finally, for STED imaging of live-cells, the most appropriate fluorescent labels are mentioned, both fluorescent proteins (FPs) and organic fluorophores which give the best performance.