This tutorial aims to show the basic steps of evaluating the thermoanalytical curves to obtain reliable data for comparison with literature data for ionic liquids (ILs). The thermoanalytical investigation of the series of bis(trifluoromethylsulfonyl)imide-based imidazolium derivatives is described. The effects of the experimental conditions, such as the atmosphere and sample pan type, on the results, are outlined. The determination of the characteristic temperatures of the decomposition is described. The difficulties in obtaining reliable data for comparison are highlighted. The advantages of applying the simultaneous TG–DSC technique are shown by comparing the corresponding derivative DTG and DSC curves. Examples of the visualization and evaluation of the data of the compound series are presented. The results of the hyphenated TG–MS measurements are evaluated. The limitations of the applied techniques are discussed, too. The principles of here described evaluation steps of the thermoanalytical curves can be generally applied not only to ILs but to most of the sample types.