This lesson is applicable to everyone, especially beginners and those who do not have access to a vocal instructor.
1. If you can't vocalise very well yet, don't try to sing like your favorite singer immediately.
Don't try to get his/her tone, expressions and volume. You can end up with a habit of using your neck muscle to control your vocal cords. Voice production at the vocal cords is actually a very natural process. e.g the vocal cord open and close 440 times in one second in order for the human voice to produce a music "A" note. Once the big bulky neck muscle get into action, the flexiblity is reduced and it will become even more difficult to sing.
Instead, try getting the pitches, or the melody right first. It doesn't matter(for a beginner) if you sing with a thin, weak, or even whiney voice. When doing this, the important thing is that you feel no stress at all. Singing pitches is a sensation you should feel 'mentally', not a resultant of body muscle fatigue.
The vocal cord is a muscle itself. Like any other muscle in the human body, it has to be trained to be strong, i.e make bigger sounds. Hence, you must let it sing at high notes by itself, not with the help of other muscles.
A simple analogy: If you always exercise your right hand with a 5kg dumb-bell, you can't expect it to be able to lift a 10kg weight with the same stamina. Using the other hand to help will not make the situation different either.[/i][size=large][/size]