For an ABS equipped car it is essential to use a pressure bleeder instead of any other means. For non-ABS cars it is merely preferable. One of the easiest ways to ascertain that the job has been thorough is to alternate between ATE blue and ATE gold, as has been suggested. The color change tells you when you've done the job, beyond blowing out the air bubbles and crud. It's a simple DIY and an important job to do regularly, and if you do it yourself you know it's been done right.
'76 Moto Guzzi 850 Le Mans