Elvis would go to the recording studio and all his band members would be there waitting … He would sit at the piano and start tuning his voice to songs. The first song he would always play and tune to was “Lead Me, Guide Me” a gospel favorite of his. He would mostly play gospel songs while other backup singers would join in singing harmony. He would do this for an about two hours while his band members would wait for him to start the recording session.
Melody Tuning
This is must to sing at the pro level. Get the sheet music, or preferably lead sheets, to all the songs that you sing. Think about the key of the song. Be conscious of every interval spacings of the notes as you play and sing the melody. This will automatically make you memorize the pitch of the notes. (This will also develop your relative pitch).
Play the melody very slow at half the song's normal speed holdinholding each the notes of the melody for a long duration.
You need to practice playing and singing the melody 100 times. Classical pianist Vladimir Horowitz would stop only after he played a song 120 times without any mistakes.
Numbers
Assign a number to each note of the scale. The root of the key is a 1. The notes ascending are 2, 3, 4, 5, 6, and 7. Listen to the melody and assign the appropriate number to the notes. If the jump is an octave just say 1 to 1. There are no minus or plus numbers. This will add certainty to your singing. Write out the melody with the numbers on a blank sheet of paper.
Chords
Later you add the song chords while you are also playing the lead notes and vocalizing them. Eventually, memorize the chords of the melody for your live singing performance.
Advanced
Become very familiar with the chord types and their inversions. There are 9 different types of chords [chord quality]. In Key of C = C Major, C Minor, C dim, C aug, C Major 7th, C dominant 7, Cm7, C half diminished, C full diminished.
Accompaniment Melody
Play on your keyboard the song chords in two different inversions so you get good at inversions and switching chords. Practice chords in both hands. You need to know the left hand rhythms and left hand note run patterns used in accompaniment. You can play the melody as an instrumental section during a break in the song that you’re singing … while playing the chords in the left hand. Do this with a metronome beat playing.