I used to twist the heater wiring but switched to zip wire a couple of builds ago. A lot easier to work with, and no difference in hum level IME. I also use point to point with as little wiring as possible. Wherever possible, components are soldered directly to tube sockets, filter caps and pots/switches. Some tag strips here and there to join components "mid air". I also try to build the layout as close to the schematic as possible (filter caps for example are placed close to the tubes they're feeding). If you're building clones/replicas this method may not be possible though, and p2p with components running all over the place at different angles doesn't have that "botique" look.