In summary, we have explored in this review various strategies for building embedded many-body Green's function methods in application to complex molecular systems. These strategies differ in many aspects: from how the environment is represented (on a lower quantum-mechanical level, using a classical model with atomistic details, or by a polarizable continuum), to how the environment effects are included in the GW -BSE calculations (intrinsically via the screened Coulomb interaction W or extrinsically via a self-consistency in total energy calculations of electrostatically coupled regions). Despite their sometimes very fundamental differences, the presented example applications to molecular dimers, molecular crystals, solvated dye or DNA systems, macromolecules, and molecular thin films show that all the strategies contain the correct physics. Preference for a particular method might depend on the actual system under study, apparently more so regarding the choice of the environment model rather than how the effects of the model are included. Therefore, the careful parametrization of models for the embedding region is a common challenge for all approaches, as is the resulting state dependence and how to include frequency dependence in the environment screening contribution.