Eliminating Vocal Break and Developing Head Voice

So many songs seem to reach into the higher registers, as I seem to need to drop the keys for the time being. However, I want to develop the head and mixed voice to where it is more "usable" in performance. Any advice or exercises to help get me there?

I recommend these three series:

https://www.30daysinger.com/tutorial/head-voice-and-falsetto-for-male-singer/1

https://www.30daysinger.com/tutorial/developing-each-vocal-register/1

https://www.30daysinger.com/tutorial/mixed-voice-101/1