I make one change to every new .bashrc file.

I change this:

  HISTSIZE=1000
  HISTFILESIZE=2000

to:

  HISTSIZE=1000000
  HISTFILESIZE=2000000

You would be surprised how useful this one change has been, answering historical questions easily, like how to generate that rsa key, or what packages did I install for that project last year.

You can usuall answer questions with ^r instead of the man page. Or maybe:

  "history | grep -C 10 <foo>"