This document gives practical guidelines for comparisons within the framework of GULFMET in addition to the Technical Supplement to the Mutual Recognition Arrangement (MRA), for the recognition of national measurement standards and of calibration and measurement certificates issued by National Metrology Institutes (NMIs), and the BIPM document Guidelines for CIPM key comparisons. These comparisons may be GULFMET key comparisons, supplementary comparisons, bilateral comparisons or even pilot comparisons for the validation of new devices and /or new measurement techniques.