A while back I downloaded an app out of curiosity, ATC4Real. It’s a mobile ATC simulator that utilizes real world navigational data, so like now with Infinite Flight, you can clear aircraft to descend via a STAR. The user interface is acceptable but nothing compared to what Infinite Flight’s is, plus you aren’t controlling people, it’s just you and a machine that fires bot aircraft at you.
Using STARs to control either Approach or Center can be very different, it’s a way of operating we’re not used to. What prepared me though for using procedures in Infinite Flight was ATC4Real. I would highly recommend you download that app and try to vector aircraft in safely using the STARs in-app.
It’s a lot more speed command usage, you’re having them descend on their own following the STAR and it will help you get used to the different strategies you will need to use. A lot of it is timing, if you’re off then you’ll begin to have unavoidable conflicts.