before singing, vocalize. you might've already heard of it. and, use your diaphragm. your breaths should be pulled from it, and NOT from your chest. when you inhale air, and your shoulders do NOT raise, it indicates proper breathing. try breathing while lying on bed. notice that your "tummy" moves up and down, and not your shoulders. practice doing it that way. another thing, get to know your speaking voice and your singing voice. i don't really know how to explain it here, but those two are different. try talking while holding your chest. if it vibrates, it means you're not singing. this actually doesn't matter for most singers nowadays but it's still better to use it because is it necessary to create a powerful sound or voice. i've got a lot more, but it's kinda hard to type everything. hope these helps.
former choir singer