Tratak is a visual technique that helps focus concentration. It requires the eyes to be partially closed as they gaze upon one object intensely for a period of time. Try not to blink or take your eyes from the object. Then, close your eyes and visualize the object in your mind.
One of the best ways to try Tratak is by gazing at the flame of a candle for as long as you can. Place the candle at eye level in a darkened room Stare at it for two or three minutes before closing your eyes. Once you close your eyes, you will be able to see the glow and shape of the candle in your mind.
Some individuals use a flower or other object. Again, this is a matter of personal preference.