make jump first so you dont limit yourself to the space of the wall you made
You make the jumps first and you ignore everything that isn't part of the actual jump.Make a big box with the Cordon Tool and work inside of that. https://developer.valvesoftware.com/wiki/Hammer_Cordon_UsageIf you want to make a dev texture map, then it doesn't really matter though. This is only important if you want to do detailing and make the map look natural. Doing the walls first might actually be helpful if you want to have rooms with the same dimensions and tele doors and stuff.