The correct answer should be by invoking their muse
The muse is a source of inspiration. If you look at Iliad, he starts by saying "Sing, O, Goddess", where he mentions the muse as a goddess because she is the one who enabled him to tell the story with her inspiration. This is quite common in ancient Greek Epics. The Greek gods are however mentioned later and are often the central part of all epics, aside from heroes since usually the course of things is that they made a mess between each other and the people are the ones who have to suffer the consequences.