Make sure you're standing straight: the vocal folds aren't "interfered" with anything else in your throat, your larynx is straight, and you're standing tall.
Your diaphragm is this big...balloon-ish thing that is the main muscle which controls the rate that your breath escapes your mouth. Make sure that is strong, and you're not from your throat, which can lead to bad things and is pretty uncomfortable anyway.
It just might be that your voice is naturally quiet. If that's the case, you have to work on projecting. Everday, try this exercise: Use your diaphragm, take a deeeep breath and just let out easy "ah"'s. Gradually, let them get louder to the point where it's loud enough for you without it being uncomfortable in any way.
If you're experiencing "breathiness" that might lead to having a quiet or thin voice, experiment with placement with your soft palette. That can alter the sound that you produce.
This is my signature.