If you love to draw, like I do, chances are you started out by copying your favorite comic-book artists, which is great. But you are going to have to move beyond studying just the lines, you are going to have to learn how to compose and simplify.
A good cartoonist has a strong foundation in drawing. And that foundation hasn't changed since the Renaissance. I know it sounds funny, or rather not, to begin with formal drawing, but that's the way to go. Sign up for drawing classes at your local community college. Be prepared to draw naked people, because life drawing is a basic foundation. And especially learn about something called "gesture drawing". That teaches your eye to see form and movement. It will mean taking your sketchbook out somewhere and drawing the people who are walking by. Sound tough? It is! That's why a lot of people never get very good at this. I've been doing it all my life and I am just starting to get it.