Sandra Bell-Lundy shares some of her childhood drawings (like the "Mad Whirly Bird: comic above) and tells parents about encouraging talented kids:
Buy them wads and wads of paper and pencils and pens and Sharpies and whatever else is their drawing tool of choice....AND LEAVE THEM ALONE.
Let them draw whatever they want. Weird perspective, inaccurate body dimensions, scratchy nothingness, uneven lettering...whatever and however they doodle, it's not wrong or something to be "improved upon". Let them have fun. Let them be immersed in their own world. Let them be minimalist or realistic or crazy-detailed or mimic other cartoonists.