Choose a song. The folk music catalog is extensive, from old call-and-response slave songs to Bob Dylan. The song you choose will be determined by your vocal range, and your preference. For example, if you want to have a folk sing, which is a group of musicians singing folk music, your selection should be standard and without much improvisation. This will make it easier to have a sing-along. Old hymnals are also considered folk music, and are ideal for sing-alongs.
Determine your music style. The song's region of origin effects the style of written music and the way it is sung. New England folk music is effected by the Irish style, declamando, which is a recited piece of music that can sometimes be monotonous in sound. These songs are sung as written without any embellishments, and are therefore the easiest to sing. Appalachian folk music is completely different. The music is embellished, and singers often sing with a thick, raspy tone, and a closed throat. Songs are often heavily embellished to invoke emotion. Great plains music is similar in nature, however, the tone is richer as musicians relax the throat while they sing.
Practice a few regional songs, and perfect your style. Either sing with your throat tight for an Appalachian style or sing the music as written, with your throat open. You can compare the differences by singing the same line with both styles. First bring your chin toward you, which should allow you to feel the back of your throat closing. Sing the line. Next, bring your head up, so that you are looking straight ahead with your neck relaxed. Sing the same line. Decide what sound you prefer and follow through. A successful singer is confident. The important thing to remember is that folk music is less about the singer than it is about the song's message and the gathered people.
Invite your friends to a folk sing. Folk music is meant to be shared with others, as a way to bring people to together. Practice together, and learn from the other musicians. This will help you gain confidence as you improve your vocal style.