Due to her mighty powers and miraculous stories, Avalokiteshvara has been an important Bodhisattva for all Buddhist schools. Each school has its own practice and rituals, but all of them are beneficial to our spiritual practice. You can follow the practice that best suits your own preferences.

In the Mahayana tradition, there are no strict requirements for spiritual practice and rituals, as "mind" is the focus of training. In the Vajrayana tradition, however, disciples are required to follow clearly defined, step-by-step rituals and practices established by spiritual gurus.

This is designed to ensure predictable progress of disciples, so they will not wander from the right path. You can follow the visualization ritual below if you want. Of course, it is more desirable if you receive empowerment from a qualified master before you start this visualization.

Before you start, sit comfortably in an upright posture. Leave all thoughts about yourself behind; stop worrying about your money, relationships, health, etc. Discard all your selfish desires and wishes.

In order to become connected with Avalokiteshvara, you must cultivate your compassion by thinking. "I am doing this visualization for the benefit of myself and all sentient beings."
After you have become Avalokiteshvara herself, start your recitation of the six-syllable mantra.

Imagine there is a moon charka in your heart with a sign of「」, surrounded by the revolving characters of 「」OM MA-NI PAD-ME HUM. The chakra emits radiant white light, which cleanses bad karma of all sentient beings and turns them into Avalokiteshvaras. At this time, the vast expanse is filled with innumerous Avalokiteshvaras.
After you give your blessing with the white light, cleanse your own bad karma by deflecting the light toward yourself. When this visualization is done, recite the mantra as many times as possible. When the recitation is over, imagine yourself vanishing into the vast expanse without any attachment and settle your mind in a deep meditative state.