saagarjha

This is zsh specific, but here's something I've been burned by enough times that I specifically wanted to mention it: save your history in a file other than the default one. Why? Because if you increase the history limit, and your profile isn't sourced for any reason, the shell will read your history file and use the default history size, clobbering everything that's there. If you use a non-default history file this rogue shell (missing your settings) will dump its history into the default file and leave your custom file untouched.

misnome
I got burned a couple of times in the past with bash-history, and go a small step beyond this, even on zsh, and added to .zshrc:

    preexec_custom_history() {
      echo "$HOSTNAME $$ $(date "+%Y-%m-%dT%H:%M:%S%z") $1" >> "~/.fullhistory"
    }
    preexec_functions+=(preexec_custom_history)
I work on a lot of shared-filesystem computers, and so it's useful to be able to filter for commands ~year ago when I know what computer I was on when I ran it. I have a fzf binding to search through this with ctrl-r, and it's otherwise easily greppable.

When I was still using bash, I had this same thing using https://github.com/rcaloras/bash-preexec .