I saw your forum post about this..
First of all, I would increase the frame rate. I animate on 20 fps, but 15 is good too. When planning your next Flash project, PLAN is the key word there. Even for a little 20-second animation, you need a vision of where you're going with it. Storyboards are super-helpful; you can see what does and doesn't work. It is a safe zone for creative thinking. As far as visuals go, try to make the backgrounds more interesting to look at. Unless that is the style that you are going for, the sky will be multiple shades, depending on the time of day, and the same goes for grass too. You may consider investing in a graphics tablet, if you are serious about becoming good at Flash. However, I know people who do fine with just a mouse, so it's a matter of personal preference. You can check out flashkit.com for free sfx and music loops, or you can get music from right here on Newgrounds. Trust me, music makes everything better. Good luck with your future projects!