If you're going to do it, do it in style! Depending on your skill, you can combine your attacks to increase your score.
One example is the 'triple kill and kick.' This high-level tactic will give you 100 + 200 + 400 + 1000 points. Other variations of this tactic can also increase your score. This 'double stomp' tactic will change the 100 + 400 score into a 100 + 500 score. There is a tactic called 'wait and re-stomp' where you can wait for the Koopa to revive after you stomp it, and then stomp it again for a high score. If you do this enough times, you'll get an extra life! When you use the Koopa shell to defeat the other enemies, your score will increase with each additional kill (500, 800, 1000, 2000, 4000, 5000, 8000, 1-up).
When you stomp on two enemies at a time, your score increases accordingly (100 + 400).