1.learn to sing a major scale,DO RAY ME FA SO LA TE DO,UPWARDS AND DOWNWARDS.
2 take a note from an istrument,for men,try the sixth string of a guitar open,sing a major scale.
3.move up a fret start again.do this six times,moving up a fret each time.
4.if you have found where you are most comfortable singing,start again,but now try singing different intervals,of the major scale.
5.practise taking deep breaths from the diaphragm, then release the air slowly,take a deep breath and release it quickly[cleansing breath]
6.now take a guitar or piano/keyboard,and try singing a chromatic scale for example starting on middle c,..c c# d d# e f f# g g# a a# b c,listening to yourself and the instrument,then do it coming down,this sort of thing helps you to sing in tune.
7 then try singing one long note, make sure you are breathing from the diaphragm,then take another note from an instrument and sing it long.
hope this helps. it may not be perfect but it is a starting point
Dick Miles