We discuss different ways to improve the analysis. The purpose of this practical guide on the aspects of quantitative XPS is first to put the reader in a position to be able to understand and judge the meaning and possible errors in atomic concentrations based on analysis of peak intensities, which is the standard way quantitative XPS is reported. This has led to an increase in the number of users who may not have a full understanding of the details of XPS and consequently must rely on the report provided by the XPS center. It is, therefore, increasingly used as a routine analysis technique to complement other techniques. XPS is one of the most widely used methods to characterize surface nanostructured samples, and XPS is now also commonly accessible to most material scientists through XPS facility centers. This guide is intended for both the novice in x-ray photoelectron spectroscopy (XPS) as well as users with some experience.