Search the forums for Whit's excellent tutorials on Po Boy Trace.
Here are the basics:
I've got a Corel file and an Illustrator file of this trace but for some reason I'm not able to attach them to this post. Maybe I've missed something in process or in the latest forums format update. Hopefully a moderator will come across this and bring me up to speed.
Anyway, these are the steps that will allow you to expand your clipart collection.
Practice and good luck!