The article outlines challenging issues regarding the preparation of materials when appointing a forensic trace evidence identification examination. Requirements for comparative samples are analyzed. The authors mention the necessity of analyzing features of the trace formation mechanism, adequacy of displaying the identification features of the trace-forming object in the traces under investigation, and the comparability of the identification complex contained in the comparative samples. Attention is focused on the expediency of involving a knowledgeable person at the stage of appointing the examination to prepare materials provided to the expert, as well as on the requirements for such person's competence and expertise.