There are ways to improve your voice for free. The most important for the beginner is to sing along with songs you like to strengthen your vocal muscles. You need a place to do this that gives you privacy and freedom to really open up volume wise.

Record yourself and be tough on getting the notes right. Don't hit close to the note and move onto pitch. Hit the notes right on and pronounce your words clearly.

Stretch your range. Push yourself to hit a higher note but don't give yourself a throat ache.

If you have any religious affiliations there is nothing like joining a church choir to not only improve your singing, you will learn to read music. Its not something that you here much about but the ability to read sheet music and possibly learn to write music will set you apart in the world of professional singer songwriters. Nothing compares to standing next to the piano and they hand you a piece of sheet music you have never seen before. The piano plays the intro and you begin singing…

A beginner's instinct with singing is to sing with their throat and to sing higher notes they put their chin up. This is all bad because it causes strain and damage to your voice. Singing lessons help your vocal health and help you learn to sing comfortably. It would be a good idea to learn from a certified professional to avoid all of these risks.

I suggest you take singing lessons on books. It is perfect for shy people and if you practice daily you will gain more confidence. Some people actually learn better with books because you learn at your own pace. The only down side to this is that your book won't remind you that its time to practice.

Some books I recommend are "Singing for Dummies" and "The Complete Idiot's Guide to Singing". They are very good books because they teach the traditional way with classic music. These books come with audio CD's so you can hear how the vocal exercises sound.

Alright.
Dude.
Come on.
You have to get up there and just sing your heart out.You said that you dont have a good voice heck then SING LOUDER!You are supposed to go there to sing better. You know every one is bad at first. Well maybe not everyone but.And it will NOT be perfect because NOTHING is perfect! And what if Hayley Williams was to shy to sing then we would never have PARAMORE!
What if your fav singer was to shy to sing in front of people then you would be a nobody stuck in a corner because you dont listen to any goood music! All of the lessons are different so idk how your people will start it. And at my town it is a tiny group. And like i said the lessons are all different so idk the costs. CHASE YOUR SINGING DREAMS!
Dont you dare back down after i have written this monster of a thing. GO FOR IT! BE THE BEST YOU CAN BE! MUSIC = LIFE!