I used to be a really shy person. I learned to use my voice by teaching fitness classes and this made me not shy. I made great strides in being more forward with people during the first year I was teaching classes.
I can tell you a couple things that will help you use your voice better. I do healings to help people use their voice, most of them are on their throat chakra, and some on self-esteem. I also taught kundalini yoga and there are some aspects of that yoga that can help your throat chakra. For example, chanting can help your throat chakra. So can singing. Some foods and drinks are good for your throat chakra and voice. Berries and juice are both good for your throat chakra.
Other things that help your throat chakra are speaking well and speaking honestly. You can state your feelings and state what you want and this will help your throat chakra and will make your life better. It is really good to make your life better to have your throat chakra be balanced. It makes you very good at manifesting what you want in your life. You can create a more wonderful life with your voice. You can do things that you could not imagine because your voice creates a lot of what you experience.