: But then what? First of, what are layers even good for?
Different motion tweens, and just plain organizing your stuff
: Secondly, how can I just simply get more fluid animation (other than adding more frames).
Umm, add more frames? Seriously, that's how you get stuff more fluid.
: I just need overall advice to take my animations from average to expert.
Okay, you want to become an expert on stick figure animation. Here's what you do. Find the best stick figure animation you can. Imagine something even better. Make it. Come up with stuff that's never been done before. Work as long as it takes to make this animation. If it takes 6 months, then work on it for 6 months. The people who make amazing flash animations spend absurd amounts of time doing them. Stick figure animations don't really take much artistic talent, so that's even better for you. You can stick to simple frame by frame animation. All you need to do is just put massive amounts of hours into it. That, and your initial idea needs to be good. Creativity. Time. That's all it takes.