When working in a terminal, many people use Bash, “one of the most popular UNIX shells” (Wikipedia). A bit more sophisticated users probably know about Fish, Zsh, or Bash-it.
I want to tell about Oh My Zsh, “the Zsh configuration management framework.” It’s like Zsh with plugins, themes, and helpers.
Even if you already use OhMyZsh, look at the plugins list, maybe you will find something useful (e.g., common-aliases, alias-finder).
Themes: https://github.com/ohmyzsh/ohmyzsh/wiki/Themes
Plugins: https://github.com/ohmyzsh/ohmyzsh/tree/master/plugins
And lastly, I recommend zsh-autosuggestions
which adds hints to incomplete commands based on history, like in Fish.
https://github.com/zsh-users/zsh-autosuggestions (can be installed as OhMyZsh plugin)