Tips for Goo Ult?

I’ve been playing viscous over the course of a week and a half now, and I’ve been having a lot of trouble with using the his ult. It actually feels as if I have gotten worse with it every single game I play. I’ve also tried just free styling the ult in the map explore mode but it just doesn’t seem to help with actually hitting moving targets in the game. I’ve tried to look up guides, but there are very few, and most are pretty dated. Any tips for getting good with balls?