Beliefs

Hellenists know the gods as individual personalities which are mostly characterized by their immortality. The gods are neither understood to be almighty, omnipresent nor authorities in ethical issues.
Head of the olympic pantheon is the mighty Zeus, who is worshipped as the ruler of heavens. Beside him there are at least the other 11 gods of the Dodekatheon who are to be worshipped (these are: Hera, Apollon, Artemis, Athene, Ares, Aphrodite, Hermes, Hestia, Demeter, Poseidon, Hephaistos). In addition some Hellenists also honor lesser gods, demigods, heroes and other devine beings.

Beside this you will hardly find any dogmas or binding doctrines in Hellenismos. Many Hellenists argue that it is rather an orthopraxic ("doing the right actions") than orthodox ("right beliefs") religious system. So it's more important that you actually worship the gods in the right manners and live a pious life (from the hellenic point of view) than what your personal beliefs are.
Nevertheless there is room for theology, discussion on the gods and the kosmos, in Hellenismos too but this belongs more to philosophy than to religious teachings.