The term “ranging” is often used to indicate the operations that make it possible to estimate the distance between two nodes by processing some signals generated and/or received by the nodes. In wireless systems, a very popular ranging method makes use of the radio signal strength (RSS), which is a measure of the received radio signal power. However, RSS-based ranging is considered very inaccurate, particularly in indoor environments, mainly because of the randomness of the received signal power. In this tutorial paper, we provide an in-depth analysis of the main factors that affect the variability of the received signal power and the accuracy of the RSS measurements. Starting\ud from a survey of the most common and widely accepted models for the radio signal propagation and the RSS-based ranging, we\ud then focus our attention on some technological and procedural pitfalls that are often overlooked, but may significantly affect the\ud accuracy of the RSS-based ranging, and we suggest possible techniques to alleviate such problems. The theoretical argumentation\ud is backed up by a set of empirical results in different scenarios. We conclude this paper by providing some best-practice recommendations\ud for proper RSS-based ranging estimation in wireless networks and discussing new approaches and open research challenges