Even if you write your program with Bash, you have to think about the user. To improve the program interface, you can use special escape sequences to highlight output.
printf -- ' doing something... \n';
printf -- '\033[37m one more output \033[0m\n';
printf -- '\033[32m SUCCESS: yay \033[0m\n';
printf -- '\033[33m WARNING: hmm \033[0m\n';
printf -- '\033[31m ERROR: foobar \033[0m\n';
You can use escape sequences to highlight some of your output. Don’t forget to turn it back with “\033[0m”.
Also, not all terminals supports escape sequences check it out before use them.