You have here some non-manifold geometry as internal edges, badly made faces (one face across 3 prepared quads), ngons and for some parts you will need support geometry (to eliminate shading issues and hardening edges). Subdivision Sufrace modifier don't play along with those. You will need to have quad based topology with proper edge flow.
As for this particular question there is too much to cover on how to repair every broken part, I would encourage you to have a moment to redo the whole mesh having in mind quad based topology. Also, use Mirror modifier so you will not need to make changes on both sides (there are some differences now).
Look for example at this topology:
Also you can learn something from here: http://topologyguides.com/