For people who are new at art, or new at a different medium.
Keeping what I call "the three Ps" in mind will help you power through and not quit before you've reached your goal.
I. - PRACTICE
It sounds cliché, but practicing is necessary; not just for art, but for everything. Much like athletes spend years in the youth levels, learning the skills, before they can become professionals... and then even when they're pros, they go to training every day, to hone their skills. Just like they do, so, too, must an artist practice.
Practice can be anything. It doesn't mean you must shade so many spheres before you can-- no! You can shake it up!