Drawing is about practicing!
Like any other skill worth acquiring, drawing also requires practice and determination. Masters often draw their subjects several times before they actually begin to make their final drawing. Try this little experiement yourself: Draw the same subject three times and pick out the differences. I am sure each time you draw the same thing it is a little different. May it be for better or worse, eventually it is up to the artist to choose which of these drawings he or she thinks is best.So just relax and enjoy the process of it.