We report here the state of development of photoemission diffraction from core levels as a tool for the investigation of surfaces. Experimental procedures for performing reproducible and accurate photoemission diffraction curves are formulated. To this end, the merit and the limitations in the choice of different parameters, such as photoelectron kinetic energy or detection angles, are discussed in view of various applications. The discussion is largely exemplied from our experiences, as well as from those in the literature.