Cryptographers, teach me how to shuffle cards

Shuffling cards is hard, some methods need skill or are to hard for children to do, others don't shuffle the cards well, sometimes the same cards easily stick together. A solution I found is to shuffle cards by distributing them into 4 piles one by one, and then putting the piles on top of each other. It usually does the job of splitting cards that were together previously, and even a child can do the procedure producing a relatively well shuffled deck. But for some card games that doesn't work: like Skip-bo where the cards end up in sets of 12 making this method terrible. I tried adding some randomness by randomly picking the piles to place the cards into, but I don't feel like it is a good solution. So, Cryptographers, use your hashing and encryption knowledge to come up with an algorithm that could be taught to a child, doesn't take more than 2 passes through the deck, but that best eliminates any kind of patterns out of cards. As criteria I will set "being able to shuffle a deck of cards that is sorted or has a repeating pattern" while "requiring the minimal amount of logic and movements from the shuffler." Maybe, I phrased my entire question badly, but I hope it can be understood.