One of the biggest trouble spots for singers, particularly male singers is taking the chest voice up into the higher notes, afraid to flip, or better yet slide, into the head voice. The reason this is important is because your chest voice can only go so far up, which isn’t very far, without strain and tension. In the head voice you have much more range. The head voice needs to be worked out and strengthened, of course, but it will be your best friend on the higher notes, if you want to sing high notes easily and without strain. But how do you find your head voice?
The first place to start is with a hum. The hum will allow you to have connection (vocal cord closure) more easily through what is called your mix, through the transition between your chest voice and your head voice. Hum at about speech level and slowly increase pitch into your higher range. That’s your head voice up there and an easy way to find it.
Another good way to find it is doing the same thing with the “ng” consonant sound. It’s a pharyngeal sound, called this because is resonates primarily in your pharynx, located just behind the base of your tongue near the epiglottis. Vocalize on the “ng” consonant allowing the sound to come out of your nose. Notice that as you rise you can get into your head voice easier and more smoothly.
Hope this helps!