There's an animation adage I've heard a couple of times -- I'm not sure who said it, or where I heard it -- but it's pretty dead-on:
"A new animator wants to put more drawings in, a seasoned animator wants to take more drawings out."
I'm paraphrasing here, but the saying is so very true. When I first got into animation, I felt that in order to do a great scene, that all I had to do was to draw some great key poses and then in-between the heck out of it. What happened was all the motion and movements looked labored, as if all my characters were moving in molasses. Not only did the action look slow and lumbering, but it also looked so amateurish. I did not take the time to realize that maybe more drawings DID NOT equal better animation.
The more experienced an animator you become you start to realize that not only do you tighten your movements by economizing your drawings, but the most important thing for you to know is where to economize; where to tighten. How to know? Practice. Do extensive penciltests. Over and over. The more tests you do, the more you learn. Eventually, you pick up on your own style of animating, unique to you, and you alone. And once you establish a style, the easier it becomes to get the job done. What once took you 20 drawings to complete, you can now get the same effect done in 10.
The same could be said of practically any job, I guess. Practice. Just keep drawing. Even if you're not an animator. Sharpen those skills. It'll benefit you in the long run.