Funnily enough, the best sources would actually be literature from the Greeks and Romans themselves. Hesiod's Theogony explains the Greek god pantheon from the very creation of the universe to the Titanomachy. The Iliad and the Odyssey by Homer, although going into their own stories, show the Greek gods acting in ways that was consistent with the ancient view of the gods at the time (i.e. as forces of nature). The same can be said for Ovid's Metamorphoses and Virgil's Aeneid. From all these alone you can get a good idea of how people used to worship the gods along with their whole moral code in general.
If you're looking for more scholarly stuff, books like "The Cambridge Companion to Homer" and "Prolegomena to the Study of Greek Religion" might help. I like these two as they do draw from ancient literature and quote extensively from the original sources (though some of the quotations may be in Greek).
If you're looking for more scholarly stuff, books like "The Cambridge Companion to Homer" and "Prolegomena to the Study of Greek Religion" might help. I like these two as they do draw from ancient literature and quote extensively from the original sources (though some of the quotations may be in Greek).
Read "Theogoneia" of Isiodos to start it off.
https://www.greek-language.gr/digitalResources/ancient_greek/library/browse.html?text_id=2&page=1