Breathe from your diaphragm whenever you sing. The diaphragm consists of an involuntary muscle that we have some conscious control over.
Warm up your voice properly by drinking tea with honey to help warm and lubricate the vocal cords. Then proceed to buzz the first five notes of a major scale starting on middle C. Find middle C on the piano by looking for the white key to the left of the set of two black keys that are closest to the center of the keyboard.
Find your singable range by singing middle C and then extending your range downwards by half steps. Use a piano to ensure the pitches are sung accurately. Play by half steps until you can't sing lower comfortably and with a clear tone. Write down your lowest note on a piece of paper using a pencil.
Sing by half step from the lowest part of your range to the highest part of your range. Feel for any difference in voice quality changes as you ascend the scale. The point at which your voice quality changes and you feel a shift between your chest voice and head voice determines your passagio. The passagio consists of the change between your registers. Write the note at which your vocal register changes down on a piece of paper.
Continue to sing to the highest portion of your range into the falsetto portion of your range. Falsetto occurs when you feel your register change into a thinner, more narrowly defined timbre. Write down the highest note that you can sing comfortably.
Determine your vocal register. A tenor will have a passagio between the notes D and E and be able to sing from an octave below middle C to an octave above middle C. A bass will be able to sing down to the F below the tenors low C and up to an E above middle C. The passagio for a bass falls between A flat and A.
Evaluate whether your voice fits more appropriately in the countertenor or baritone range. The countertenor has a range from G below middle C to F on the top of the treble clef line. Countertenors have a passagio that exists on an F above middle C or higher. The baritone voice has a range between A flat below middle C and A flat above middle C. The passagio for a baritone falls between A and B below middle C.