A conventional vocal piece has the option of four voices.
The four parts are bass, tenor, alto and soprano
Vocal works need words. You may decide to use a poem that you can interpret or you may want to do a religious style of song. Either way you have to choose the lyrics that will fit your piece of music.
Deciding the Vocal style, here are some suggestions
Working with your lyrics.
You will want to work out where you will add stress (accents) to your words. Also where you add melisma to your work. This is call Scansion, it is where you establish the meter (rhythm) to the text.
After you understand the meter and the rhythm of the words you may want to work on your melody. You may want to work around a simple accompaniment first or add the accompaniment after. Either way the melody will be what makes the vocal piece. To help the melody you may want to
When you have your melody, think about the texture and how you can make your melody more interesting.
Most vocal pieces are in Strophic (song) form which is a typical ABA with the B a contrast of A. However some interesting ideas have come from through composed vocal pieces.
Where the lyrics and the words reflect the meaning of the song. For example using the word bright to change from Minor to Major. Or flying being modulated in a mordent or turn. In short the words reflect the music.
Make it work
A three minute melisma part is not going to be able to be sung by anyone. They will pass-out before they finish the piece. So make sure your piece is not too tiring for the vocalists. They are not singing too high or making impossible pitch leaps that can affect the performance. If unsure find a decent singer and ask them if they could try it out for you.
Finish it nicely
Tempo, Dynamics, Articulations make sure you have added these and anything else that will make your piece sound spot on.
Deadline 13th November