Transitor Goes Boom

In lieu of a motor controller board, any suggestions on the best transistor for little 3-12v motors? I know in the long run I'm going to want an H bridge setup (my robot Herbert is 4wd with now steering mechanism so maneuvering will have to be with the wheel motors) but just to mess around and understand the circuits and the code I just wanna drive the motor circuit without frying my Arduino....

Annie :slight_smile: