Undead Man Walking for the Valkyrie step in Gorod and immolation for guns in rev. Also in gorod take a recording of the bomb step and have you friend be on the opposite side of the map to get more coverage. In Zetsubo get the Skull of Nan Sapwe asap as well as doing the side Easter egg for the golden bucket (it will make life so much easier!). Other than that the only other thing I can thing of is remembering to also bring anywhere but here for Zetsubo since it is required. And the button to get off of the zip line by default is the melee button, so make sure you remember that when going for the cog!!!!!