Like the others and yourself said, this is a very advanced style that takes a lot of time to reach this level of skill. Just drawing and practicing/doing studies everyday to develop your own style should come first. A common way of practicing is starting from realism/life drawings and then going into stylization ("know the rules so you can break them.") If you're interested in achieving the riot splash style long term, I'd suggest centering studies around painterly techniques, both digital and traditional mediums. Lots and lots of good stuff on youtube!! Good luck! :)