Hello!
For both the flying and ATC aspects, my best advice is to practice, practice and practice.
If you want to know more, as Brendan shared above, there are plenty of Infinite Flight Official Guides and many tutorials on the Infinite Flight Official YT channel.
I highly suggest you to have a read of the ATC Manual from Section 1. to Section 5 if you plan to join IFATC (based on your previous topic, I imagine you are interested). Then, you can practice on the TS (Training Server) by also utilizing an ATC Tracking Thread.
Regarding the flying, remember to always follow all the ATC instructions and familiarize yourself with the flying procedures described in the guides above (especially the Flying Guide).
Feel free to ask any questions if you have any! This is a great community always eager to help :)