Numerical and analytical micro-modeling of masonry structures requires knowledge of several elasticity and strength parameters of the constituent materials of the composite. Furthermore, when dealing with specimens produced in the lab or extracted from existing structures, several problems arise concerning the limited number of samples and to their dimension ratios which will often render them inappropriate for accurate standardized testing. In the case of historical structures, the number of samples may be limited due to the need for compliance with conservation principles. This paper proposes a methodology for the experimental derivation of several material parameters of the units, the mortar and the masonry composite from a limited amount of sampled material using conventional mechanical tests. The method attempts to alleviate some of the obstacles often encountered in the experimental characterization of masonry structures, and focuses on those parameters that are most important for the simulation of masonry under compression using micro-modeling techniques. The applicability of the proposed methodology in actual existing structures is demonstrated through a case study.