Drawing a cartoon ball can be quite easy. You just need to sketch a circle and add one color to it. To make things more interesting, you can also create a nice shadow on your ball to illustrate a 3D effect.
Finally, if you want to go a little further, you can draw a ball with multiple colors and add some shadows on it. Creating a ball is easy, but applying great effects on it can be challenging if you don't have access to a vector software.
If you want to try some advance drawing lessons, then I suggest you try one (or all) of the objects displayed below. All these balls are easily recognizable and not too hard to accomplished!
Like I said earlier, these tutorials are easier to achieve if you have access to a vector software (highly recommended), but it's not mandatory to create a nice cartoon image.
More fun items related to sports can be drawn below. Have fun with these additional resources and remember to practice on a daily basis. :)