Comment by tjoff

A very common change is to change the prefix to ctrl + a, like this in your tmux.conf:

  # remap prefix from 'C-b' to 'C-a
  unbind C-b
  set-option -g prefix C-a
  bind-key C-a send-prefix

I've heard that he reason for ctrl + b is because screen uses ctrl + a, which just doesn't make any sense to me. You can nest both tmux and screen and to get to an inner layer you press (if ctrl + a has been mapped) ctrl + a + a - and now your command is sent to the inner tmux/screen.

Defaults matter. It is not feasible to configure this on every machine you touch so one have to remember both the default one and the sane one...