I find grep\'s --color=always flag to be tremendously useful. However, grep only prints lines with matches (unless you ask for context lines). Give
grep
--color=always
You can use my highlight script from https://github.com/kepkin/dev-shell-essentials
highlight
It's better than grep because you can highlight each match with its own color.
$ command_here | highlight green "input" | highlight red "output"