As a vocal coach & songwriting instructor for over 10 years with millions of streams on Spotify, I'd like to share with you some tips on writing for your voice.
Tip #1 - Range
Find the most comfortable notes that you sing. Just because they are comfortable does not mean it's easy for everyone else. This is likely a sign that you're in the sweet spot of your voice.
I recently noticed Billie Eilish singing very loud in "Happier Than Ever"
and it's around middle C despite the fact that it has so much energy. Her voice carries that energy there.
Tip #2 - Agility
Assess what you find easy. Is it easy to sing really choppy and fast rhythms like Ariana Grande or are you more of a crooner with slow movement in your vocal cords like Lana Del Rey?
"Songwriting is a muscle. The more you do it, the better you get at it." Jason Derulo
Tip #3 - Challenge Yourself
Don't be afraid to push yourself and do the opposite of you natural instincts. Pushing yourself out of habits might introduce you to a part of your voice you never knew existed.
I recently watched the Bee Gees documentary "how can you mend a broken heart" and it's fascinating to hear them discuss discovering their higher range during the Saturday Night Fever era. This was WELL into their careers and they found a whole new sound.
The most important take-away is feel your voice out and decide what's comfortable and unique. Roll with it! If you want live feedback and help writing your songs, checking out our Online Songwriting Workshop which meets several times a year!