X‐ray fluorescence spectrometry (XRF) has been routinely employed for simple and convenient determination of major and minor elements in solid and powder samples without dissolution treatment. In addition, spectrometers have been downsized and automated with the development of instrumental components and analytical techniques. Modern XRF instruments are used by not only analysts but also persons in various fields with little analytical knowledge and technique and who may not verify the reliability of the analytical results and/or sample preparation. However, the accuracy of XRF determination largely depends on the sample conditions such as flatness, particle size, homogeneity, and thickness. Appropriate conditions are identified by the analytical depth of fluorescent X‐rays. This article details solid and powder sample preparations based on the analytical depth and type of XRF specimen (loose powder, powder pellets, or glass beads). Moreover, it describes calibration curves using synthetic standards prepared by chemical reagents containing analytes. These standards are validated against reference materials (RMs) for reliable XRF determination.