Sing songs to which you can relate. The blues is a style of music that generally talks about pain, grief, loss and suffering. In order to be a really great blues singer, you have to be authentic. Choose songs that talk about issues that you have experienced in your life.
Add a low growl to your voice to sing the blues like a pro. Blues vocals should sound full and gritty.
Use traditional blues instruments to back up your vocals. Common blues instruments include electric guitar, slide guitar and harmonica.
Refrain from enunciating your lyrics too clearly. Professional blues singers have a smooth, relaxed way of pronouncing their words as they sing. For example, instead of singing, "Since my baby left me," you should sing, "Since maaahhh bay-bay lefff meeee...."
Listen to some of the great blues singers to gain an understanding of how professional blues vocals should sound. Some of these famous musicians include B. B. King, Stevie Ray Vaughn, Son House, Howlin' Wolf, Buddy Guy, Robert Johnson and John Lee Hooker.
Use a blues scale in your music. A blues scale is a pattern of musical notes that is very similar to a minor pentatonic scale. In a blues scale, you use the pattern of 1 ("root" or starting note), minor third (three half steps higher), 4 (five half steps higher than the root), diminished fifth (one half step higher than 4), 5 (two half steps higher than 4), minor seventh (three half steps higher than 5) and 8 (one octave higher than 1). The half steps in music consist of the following notes: C, C#/Db, D, D#/Eb, E, F, F#/Gb, G, G#/Ab, A, A#/Bb, B. So, if you wanted to sing the blues using the C blues scale, your notes would be: C, Eb, F, Gb, G, Bb, C. Even some modern songs, such as Adele's "Rolling in the Deep," employ the same pattern of notes or one that is very similar.