The general rules for labeling topographic maps can be applied when choosing the font, colour and size of the text. More information on this topic can be found in the GITTA module Layout Design Settings / Graphical Semiology in the chapter Typography For thematic maps, the following rules can be applied in addition to the already mentioned guidelines:

Names, that are used for orientation, such as those for landscapes or mountain ranges, waterbodies and countries, should be placed according to the actual need in textual explanation. Names are used far more sparsely. They are partly only indicated with their initial letters and sometimes even omitted completely to avoid noise. This, however, should only be done if the message of the map remains clear. Explanations describing thematic information can be omitted completely, if all necessary hues and signatures are explained in the legend. In the case where all diagrams have to be explained without having enough space to do so, only initial letters or small indices can be used, which are then explained at the map frame (Imhof 1972, p. 244f).