I'm going to share some healthy art tips because I feel that if I had someone tell me stuff like this long ago, I wouldn't have learned the hard way. Quite possibly you'll do the same if you're so inclined(its always better that way- so stop reading now).
As an artist, I thought to myself a lot about what my skills and where my strong points are. Regardless of it being doing comic book style work or life drawing.
I promised myself that if i didn't see the potential in my understanding of anatomy, i wouldn't touch comic book art. Eventually it took me a year to really know how to draw better in certain situations and overcame my hurdles.

To Students:
Not all people can draw exceptionally well in a class room or public setting (some get flustered, it happens). Bad lighting makes it hard to focus. Too strong lighting might make your eyes hurt. Too much coffee. Perspective(too much clutter in your field of view). Too hot that day, too humid. I try to make a habit to stop everything when im in no condition to draw.

Also, learn how to draw with S and C curves only, before tackling refined muscle work. Study it and read about it but don't overdo it until you get your proportions/perspectives right. Doing so makes you faster. Some people have developed their own styles using simplistic S/C curves. You'll find this alot with animation.

To Comicbook artists: Can't say much here as its all personally taste. But simpler/cleaner outlines/lines/shadows is better. That's all i 'ould say.
Your brain is your toughest critic. Its good to use it sparingly and not waste it all on drawing or else you'll end up being a flesh eating zombie.