An editorial cartoon should be simple but also cause a reaction from the reader.
An editorial cartoon is an illustration, typically appearing in a newspaper, which attempts to satirize political or cultural events in a way that's funny or at least thought-provoking. Success as an editorial cartoonist requires far more than simply possessing drawing skills. Aspiring cartoonists also need to understand make a point through the cartoon and have an ear for the news, so they can turn recent events into relevant illustrations.
Complexity into Simplicity
An editorial cartoon typically only has one frame in which to get its message across, so you'll need to turn something that could be quite complicated into a simple drawing that is understandable to most readers. It helps if you've got a clear idea of the point you're trying to make -- and make sure it is just one point -- otherwise your cartoon could become cluttered and too complex by trying to say many things at once.
Aesthetic Elements
You don't have to create a masterpiece every time you draw an editorial cartoon, but your illustration does need to be accessible and aesthetically pleasing to some extent. As suggested by the Union of Concerned Scientists, consider the lines and shapes you use, which should reflect a reasonable standard of drawing and be easy to follow to avoid readers being put off by the cartoon.
Go for Emotion
However you choose to draw the image and whatever your message, you've got to aim to trigger an emotional response of some kind in the reader. An editorial cartoon that causes no reaction doesn't say much about your abilities in the field. Typically, a cartoonist will aim to make readers laugh through her creation, so it's worth injecting humor into your work; but editorial cartoons also can be designed to cause controversy, if the issue involved is polarizing.
Target Local News
Many editorial cartoonists draw inspiration for their work from national news, but since these are events that affect the whole country, it means you'll be up against plenty of stiff competition if you're also trying to base cartoons on these subjects If you're looking to get your work noticed, try instead to draw cartoons based around the news in your area. You might draw about local politicians or scandals, for example. As the MacKay Editorial Cartoons website suggests, local newspapers need content, and this gives you an opportunity to provide it and get published.
Originality
Any cartoon must be original, and this is especially the case if you're commenting on a statewide or national issue that's likely to be addressed by multiple other cartoonists. Even if your view is similar to many other people's, you need to find your own take on any news.