Yup, it's use it or lose it--and use it and it gets stronger.

I sing every day, on the street, in the shower (2 different places), alone, in groups- including doo-wop, country and bluegrass, FSGW events, music parties, duets (Jan calls me a duet slut since I'll sing with anybody), Sacred Harp, and the Choral Arts Society of Washington-- (we usually sing in the Kennedy Center Concert Hall and just did a concert including Hindemith, Britten Brahms and Gabrieli).

Of all the sources of improvement, I'd have to say #1 for me was singing in the car for 30 years with the Beach Boys--it gave me falsetto. I have a lousy range--1 1/2 octaves.   But falsetto doubles it.    And somehow, with the help of the Beach Boys, I've learned how to smoothly make the transition. Don't try Frankie Vallee, though--that's just suicidal.

Second biggest source is, believe it or not, aging.   I think all voices drop with age. Mine sure did. I can now hit low notes ( e.g. low D) I never could earlier.   So since I have kept the falsetto I now have a good range.   With 2 octaves you can sing almost anything.


I'd also second the suggestion to join a choral group.   In a (good) choral group, you learn useful skills like sustaining pitch, breath control and chromaticism--as well as learning to sing harmony, in tune, til harmonies come easily in other contexts.

I would say you don't need vocal lessons--too many voice teachers seem to think everybody needs artificial vibrato, beyond normal vibrato.   In most situations vibrato is the last thing you want.   Anything they can teach you you can learn on your own.