Experimenting with Tantra practice is not recommended. If interested in Tantra, it is wise to consider taking an initiation into Tantra practice from a qualified Tantric Master. 

Practice of Anuttarayoga Tantra (or any other aspect of Tantra, for that matter) needs insightful guidance.

Books and links on the subject of Vajrayogini and Heruka Tantra practice and Highest Yoga Tantra system:

- Path to the union of clear light and illusory body, by Venerable Geshe Acharya Thubten Loden

- Ocean of Indivisible Method and Wisdom, by Venerable Geshe Acharya Thubten Loden

- Great Treasury of Mahamudra, by Venerable Geshe Acharya Thubten Loden

- The New Guide to Dakini Land, by Venerable Venerable Geshe Kelsang Gyatso

- Melodious Drum to Dakini Land, composed by Venerable Yangchen Drupai Dojre

- Essence of Vajrayana, by Venerable Geshe Kelsang Gyatso

- Tantric grounds and paths, by Venerable Geshe Kelsang Gyatso

- Sublime path to Kechara paradise, commentary by Sermey Khensur Lobsang Tharchin

- Modern Buddhism: The Path of Compassion and Wisdom, vol II., by Venerable  Geshe Kelsang Gyatso

- The Highest Yoga Tantra, by Daniel Cozort

- The Extremely Secret Dakini of Naropa, translated by David Gonsalez

- The Heruka Chakrasamvara Root Tantra, translated by David Gonsalez

- Source of Supreme Bliss, translated by David Gonsalez

- Vajrayogini Sadhana and Commentary, by Venerable Geshe Ngawang Dhargyey

Links to online book stores:

- Tibetan Buddhist Society >>

- Dechen Ling press  >>

- Tharpa publications >>

- Books on Yamatanka practices >>

Direct links:
- A Short Sadhana of the Wrathful Black Dakini, Tröma Nagmo >>

- A Long Sadhana of Vajrayogini >>