A non-linear frequency-domain (NLFD) methodology has been recently proposed for the computationally-efficient numerical simulation of wave energy converters (WECs), taking into account non-linear effects in the device dynamics. The primary objective of this paper is to contribute making the wave energy academic and industrial community familiar with the NLFD formulation, by giving researchers and engineers more insight with respect to the practical issues related to the method, as well as its possible application areas. The NLFD method is briefly described, and the main associated practical issues are detailed: robustness and convergence, duration and time-step of the simulations, and finally random generation method for the input wave signal. In terms of WEC dynamics, numerical applications show that NLFD allows for handling strong non-linear dynamics, provided that the WEC outputs remain smooth. The method also allows for modelling cross-frequency energy transfers. In contrast, NLFD does not seem suitable for the non-smooth dynamics related to some specific PTO designs. The small computational time associated with NLFD method makes it particularly advantageous for applications involving a large number of simulations, such as WEC parametric optimisation, power assessment, and WEC dimensioning and reliability.