Learn the Hindustani musical scale. The scale is separated into 22 intervals of 7 primary notes. Sa - Re - Ga - Ma - Pa - Dha - Ni - sa. The 7 notes, called Sur', do not have equal intervals. A group of 7 sur' is called a saptak. The first and the fifth notes, or Sa and Pa notes, will never change their place on the 22 count interval, while all the other notes can be changed around for different rhythms.
Exercise your body first with light exercise. This will get rid of any muscular tension to keep the singing voice from being strained or tensed. Exercise also stimulates deep breathing which is important for good voice support.
Begin singing in your most comfortable vocal range so that you don't strain your throat muscles when you start off cold. Move down the scale to the low note of 1 or Sa. Hold that out as long as you can over and over.
Move up and down the scale of the 7 primary notes, going faster each time to warm up the vocal cords. Go up to higher notes on the scale, even another octave up if that is in your voice range. Be careful not to strain your voice.
When you have finished performing or practicing, it is just as important to cool down your voice with exercises that soothe the vocal cords. Go into soft descending scales down to the Sa note. If you don't take the time to cool down, the tension on the vocal cords will stay tensed.