Apart from books and sheet music, your most important source of information will be recordings. Listen to albums which feature great singers. Regardless of the style of music you prefer to sing, it is important to listen to many different styles, in order to hear the widest possible variety of interpretations and expressions. There is something to be learned from every style of music and singing.
It is a useful exercise to listen to several different recordings of the same song performed by different singers. Listen to their phrasing, their timing, their note choices, the tempo they choose, and the style of accompaniment.
By doing this with several songs, you will soon work out your own preferences as well as getting valuable ideas for how to approach other songs and how to write your own arrangements. When you are listening to albums, sing along with the songs and try to copy the sounds you are hearing.
This helps you absorb the music and before long, it will start to come out in your own style. It is also valuable to sing along with albums sometimes imitating what you are hearing and sometimes improvising. This is good ear training and is also a lot of fun.
For more books and recordings by the author, visit: www.petergelling.com