Yantras are traditional visual aids that are used both externally and internally in the practice of Tantric Buddhism. Yantras are geometrical designs that enable you to focus on an image that will help you to quiet your mind. When you become more advanced in your practice, you will be able to fully visualize a yantra with your eyes closed. Any of the standard yantras in the Tantric texts are suitable for practice. A great yantra to start with is the Sri Yantra: 

Meditation Instructions: 

1) Sit comfortably with your back straight. 

2) Gaze at the image with a soft focus. Focus on the dot in the center of the image. 

3) Allow your breath to deepen naturally as you maintain your focus. 

4) When you notice that your mind is quiet, close your eyes, relax and let go. 

5) As your mind becomes active again, open your eyes and resume your visual focus. 

6) Continue alternating between meditating with your eyes open and your eyes closed in this manner until your meditation session has ended.