Using a general symmetry-based approach, we provide a classification of generic miniband structures for electrons in graphene placed on substrates with the hexagonal Bravais symmetry. In particular, we identify conditions at which the first moire miniband is separated from the rest of the spectrum by either one or a group
of three isolated mini Dirac points and is not obscured by dispersion surfaces coming from other minibands. In such cases, the Hall coefficient exhibits two distinct alternations of its sign as a function of charge carrier density.