The secret key to using Yantras in meditation is Resonance. The process of Resonance is established by mental focus on the image of the Yantra. As long as the mind is tuned into the specific mood associated to that Yantra, the energy flows, but when the Resonance is stopped, the energy disappears.
Instructions for Shri Yantra Mandala meditation:
1. Hang the Shri Yantra mandala on a wall facing North or East, placing the center of the Yantra at the level of your eyes
2. Adopt your favorite posture or, if you want, sit on a chair maintaining a straight spine.
3. Breath in through the nose and out through the mouth, but do not force at all, just let the breath flow normally.
4. Look into the center of the Yantra, trying to blink as rarely as possible; you don't want to look at the particular details of the Yantra, just keep your sight right in the center and observe the whole Yantra at once.
This exercise should last at least 15-30 minutes every day; the experience will be indescribable.
After at least seven days of Shri Yantra Mandala meditation you will be able to tap into the same yantric energy even without a Yantra (at the beginning you may fix your sight on an exterior or imaginary point or evoke the Yantra with your eyes closed)
When executing this technique it is recommended that we maintain a state of aspiration and intense longing for experiencing the beatific energies of the consciousness.
In superior phases the shri Yantra Mandala absorbs the practitioner's complete attention, and he can no longer tell if the Yantra is within himself or if he is within the Yantra; this is the state of nonduality.
The small yantra image in this post can be enlarged (click on it) copied, and printed, and then used for this meditation. You may color it in any way that feels appropriate.