If you have no imagination, then you shouldn't be making Flash, should you? How to get better: Watch other stuff on Newgrounds. If theirs is better than yours, then you know that's something for you to improve on. Is their movement better? Improve your animation. Is their sound better? Improve your sound. Whatever. If you have no ideas, watch more stuff on Newgrounds. Don't copy them, just watch them. Eventually you'll get ideas of your own.
Exedor
If you have no imagination, then you shouldn't be making Flash, should you? How to get better: Watch other stuff on Newgrounds. If theirs is better than yours, then you know that's something for you to improve on. Is their movement better? Improve your animation. Is their sound better? Improve your sound. Whatever. If you have no ideas, watch more stuff on Newgrounds. Don't copy them, just watch them. Eventually you'll get ideas of your own.