The surest way to improve your singing voice is to take face-to-face lessons with a fully trained and highly qualified vocal coach.
While some may seem to rely on web tutorials, nothing beats the actual guidance of a vocal coach who can give you feedbacks right away on how to improve your singing voice. Relying on web tutorials alone, may lead you to misunderstood things and you will end up developing bad habits and hoarseness.
It is always much wiser to invest to face-to-face lessons rather than wasting your money to frequent visits to ear-nose-throat specialists due to the aforementioned problems. If face-to-face singing lessons are not your thing, you can also opt to join in-group singing lessons or joining a choir in your school or church is also a good alternative.
Always remember to warm up your voice properly, but please know your personal limits and don’t overdo or overworked your voice. Remember the concept of diaphragmatic support and good body posture. Do not strain your throat.
Avoid fizzy drinks and caffeinated products. They dry up your throat. You can eat all of these of course, but never before singing.
Also, avoid unnecessary shouting, yelling, screaming nor any form of voice abuse at any time. Respect the bounds of your vocal range, if your vocal teacher says you’re an alto, then sing alto.
Remember to drink at least 2 liters of room-temperature still water everyday, not just during singing days and avoid inhaling secondhand smoke if you can.