How do you add visual interest to your cartoons? Here’s some advice from the 1940′s Cartooning Course:

“In today’s competitive market, a cartoonist can’t get very far without imagination. A picture may be drawn with painstaking correctness and still be uninteresting. To be uninteresting is the greatest crime a cartoonist can commit.
When composing your panel, don’t just draw your subject so that it is recognizable. Think: can you include some action or a different viewpoint that will be exciting to the reader’s eye? Perspective, action, background – all the elements of cartooning must be considered as ingredients that can help you make interesting compositions.”

–Famous Artists Cartoon Course – Lesson 11 Pg 7