One of the keys to a great vocal is good enunciation. Very few vocalists get away with being a great vocalist without amazing enunciation these days. The ability to hear vocals helps with the emotional connection of lyrics and a clear production. However bands are often at a disadvantage in this department. PA’s are often muddy and unclear, and home recording equipment can sound like you have a towel over the sound. One of the best ways to rehearse and get your annunciation clear before the studio is to sit down and rehearse the song quietly. Whether it is acoustic or singing over a track in a room above quiet studio monitors. Have everyone else involved in your rehearsals critique the enunciation of the vocalists words and experiment till you have a crisp clear well enunciated vocal. Encourage nitpicking and try pronouncing words different ways until you have made good decisions as to the small details of your vocals. Adding up all of these small details will accumulate to a huge difference.