1) read more design and arts related magazines and books.
2) find some artists you like and get the inspation from their works.
3) go to museums and look at art works.
4) never stop drawing and doing sketches.
5) pay close attention to things that is happening around you.( it can gives you ideas)
6) keep a sketch book and keep a record of your work.( then you can see how your work being improved from time to time)
7) continue to take art classes.
Good Luck.
keep trying and drawing, someday you will be a good artist.
Trust me there is no easy way to be good, you need to work hard to recieve what you deserve.
"Rome is not build in one day"
2007-07-09 19:07:56 補充:
8) share your works with your teachers and friends to get the feedbacks and comments from them. ( so you know what you need to be to improve)