When I do japa I chant om namo Nārāyaṇāya. This is the mantra that goes along with the Mahasudarshana yantra I have, and recommended by Sri Dharma Pravartaka Acharya (aka Dr. Frank Morales). Going back to this post by dyanaprajna http://www.religiousforums.com/forum/reputation.php?p=3164966 where I initially inquired about deity yoga:
I am finding that I am not identifying with, or able to identify with God Himself, though I know He is within me. I am not able to identify with the qualities God possesses nor do I know what qualities in me to bring out. It seems like biting off more than I can chew. However, I am able to identify with Avalokiteshvara as the bodhisattva of compassion, whose mantra is om mani padme hum. Compassion is something that is surfacing, that I want to bring out fully. While Vishnu is Supreme God, I am feeling that Avalokiteshvara is the vehicle or path to developing and exposing the compassion.
I have found the Nīlakaṇṭha Dhāranī. Notice the last three lines. This could very well be a dhāranī to Vishnu and Shiva. I don't think there is a conflict, because I believe that all buddhas and bodhisattvas are but aspects of Vishnu, who as the name suggests, is all-pervading. Of course I still chant His names. I just find this very odd that I am drawn this way to a yidam I would least expect, being primarily Vaishnava.
I think that, if I understood everything I've read about Vajrayana correctly, the goal is not necessarily to identify with the deity, but to realize that you are not different or separate from the deity; that the deity is not an external form, but something inside yourself, that the qualities of said deity (compassion with Avalokitesvara, or wisdom with Manjusri, etc.) are qualities you possess, but just need to have a way to bring out.
I am finding that I am not identifying with, or able to identify with God Himself, though I know He is within me. I am not able to identify with the qualities God possesses nor do I know what qualities in me to bring out. It seems like biting off more than I can chew. However, I am able to identify with Avalokiteshvara as the bodhisattva of compassion, whose mantra is om mani padme hum. Compassion is something that is surfacing, that I want to bring out fully. While Vishnu is Supreme God, I am feeling that Avalokiteshvara is the vehicle or path to developing and exposing the compassion.
I have found the Nīlakaṇṭha Dhāranī. Notice the last three lines. This could very well be a dhāranī to Vishnu and Shiva. I don't think there is a conflict, because I believe that all buddhas and bodhisattvas are but aspects of Vishnu, who as the name suggests, is all-pervading. Of course I still chant His names. I just find this very odd that I am drawn this way to a yidam I would least expect, being primarily Vaishnava.
Tadyathā: Om Ālokādhipati lokātikrānta
(Like this: Om! Lord of Effulgence, the World-Transcending One.) Ehy mahā-bodhisattva sarpa-sarpa smara smara hrdayam
(Come, great bodhisattva, descend, descend. Please remember (smara) my heart dharani.)
Kuru-kuru karma dhuru-dhuru vijayate mahā-vijayate
(Do, do the work. Hold fast, hold fast, Victor, the great Victor)
Dhara-dhara dhārinī-rāja cala-cala mama vimalā-mūrtte
(Hold on, hold on, King of the Dharani. Move, move onto my spotless image.)
Ehi ehi chinda chinda aras pracali vaśa-vaśam pranāśaya
(Come, come, the vow, the vow of the admantine king, destroy, destroy every poison.)
Hulu-hulu smara hulu-hulu sara-sara siri-siri suru-suru
(Quick-quick, please remember, quick-quick. Descend-descend, descend-descend, descend-descend)
Bodhiya-bodhiya bodhaya-bodhaya maitriya Nīlakantha [dehi me] darsanam
(Being enlightened, being enlightened; enlighten me, enlighten me. Merciful Blue-necked One appear [unto me].)
Praharāyamānāya svāhā siddhāya svāhā mahā-siddhāya svāhā siddhayogīśvarāya svāhā
(To you who sees us, hail! To the Successful one hail! To the Great Successful one hail! To the Successful Lord of the yogis, hail!)
Nīlakanthāya svāhā varāha-mukhāya svāhā narasimha-mukhāya svāha
(To the Blue-necked one (Nīlakantha) hail! To the Boar-faced One hail! To Man-Lion faced One hail!)
Gadā-hastāya svāhā cakra-hastāya svāhā padma-hastāya svāhā
(To one who bears the mace (gadā in his hand, hail! To the holder of discus in his hand, hail! To One who sports a lotus (padma) in his hand, hail!)
Nīlakantha-pāndarāya svāhā Mahātali Śankaraya svāhā
(To Blue-necked One smeared (with holy ashes), hail! To the mighty auspicious one, hail!)
(Come, great bodhisattva, descend, descend. Please remember (smara) my heart dharani.)
Kuru-kuru karma dhuru-dhuru vijayate mahā-vijayate
(Do, do the work. Hold fast, hold fast, Victor, the great Victor)
Dhara-dhara dhārinī-rāja cala-cala mama vimalā-mūrtte
(Hold on, hold on, King of the Dharani. Move, move onto my spotless image.)
Ehi ehi chinda chinda aras pracali vaśa-vaśam pranāśaya
(Come, come, the vow, the vow of the admantine king, destroy, destroy every poison.)
Hulu-hulu smara hulu-hulu sara-sara siri-siri suru-suru
(Quick-quick, please remember, quick-quick. Descend-descend, descend-descend, descend-descend)
Bodhiya-bodhiya bodhaya-bodhaya maitriya Nīlakantha [dehi me] darsanam
(Being enlightened, being enlightened; enlighten me, enlighten me. Merciful Blue-necked One appear [unto me].)
Praharāyamānāya svāhā siddhāya svāhā mahā-siddhāya svāhā siddhayogīśvarāya svāhā
(To you who sees us, hail! To the Successful one hail! To the Great Successful one hail! To the Successful Lord of the yogis, hail!)
Nīlakanthāya svāhā varāha-mukhāya svāhā narasimha-mukhāya svāha
(To the Blue-necked one (Nīlakantha) hail! To the Boar-faced One hail! To Man-Lion faced One hail!)
Gadā-hastāya svāhā cakra-hastāya svāhā padma-hastāya svāhā
(To one who bears the mace (gadā in his hand, hail! To the holder of discus in his hand, hail! To One who sports a lotus (padma) in his hand, hail!)
Nīlakantha-pāndarāya svāhā Mahātali Śankaraya svāhā
(To Blue-necked One smeared (with holy ashes), hail! To the mighty auspicious one, hail!)