There are no really "modern" methods ... You should recognize and analyze the structure, the symbols, the (classical) rhetoric, allegories, you need psychological knowledge, you should know a good part of relevant literature and you should read what you like and like what you with, an open mind. For some literature very useful ist the theory of the heros journey (Campbell ...), C.G. Jungs theory of the archetypes ...a bit of philosophy (Plato, Aristoteles) hermeneutics, I prefer Schillers theory of asthetics, but in the academic field some of them are not really welcome ...