There is no practical relationship of Bhakti Yoga as other practical yogic theories even it is very practical not with physical exercises ratherthan mental purification and devotion. In fact, for Bhakti, culture is the important phenomena. Culture not due to religeon. Culture what the children get from their parents from childhood till the adult. If family gives also spiritual treatment and believe to the children then they will have at least qualitiy to devote or trust. Bhakti yoga is not possible without trust and speaking truth. It gives itself one craft is love without benefit and this improve the purity. This purified love towards God is Bhakti and to get the achievement through this process is Bhakti Yoga.
Many small facter is important and responsible to get intrest towards Bhakti. For example: treatment of family in respect to love, trust, God, vegetarian food, love with animals, compassion and sympathy towards sick and poor peoples etc.
In Bhakti Yoga, more action of the mind than the body. If any child get this treatment in the childhood, there is possibility to bend towards Bhakti Yoga. Some time emotional peoples think also that Bhakti Yoga is suitable for them but being emotional is not only enough phenomena. Emotion is not the proof to being devoted but devoted person can be emotional so, it can be not true theory that emotional peoples can practice Bhakti Yoga.
Proof of Bhakti Yoga you can find everywhere in every religion. So, this means not that only some certain kind of religion comes under Bhakti Yoga. Pure love and enough trust is important and it can be in any religion.
If we see also little back in history then we will find that approximate every yogi, every great peoples were anyhow were attached towards God with devoted and trustful mind.
Shri Patanjal, Ramkrishna(Guru of Swami Vivekanand), Dayanand Saraswati, Guru Vashistha, Sharbhang Rishi, Parini, Guru Yagyvalk, Baba Gorkshanath, Chaitanya Mahaprabhu, Surdas, Shirdi Saibaba, Das Maluka, Sakha Sudama, Bhakt Hanuman, Narad Rishi etc. Some are without any yogic practice got achievement just due to bhakti and they becomes great yogi such as Chaitanya Mahaprabhu, Shirdi Shaibaba, Surdas. Tulsidas, Bhakt Prahlad(even he was in the demon family), Kalidas, Jesus(He bocomes as a God due to his Bhakti towards God).
The Yogi who were in the field of yoga also mentioned to practice of Bhakti Yoga. Shri Patanjal has written in his ashtanga yoga 'Ishwar Pranidhan', means devotion in God. Shandilya has written, 'Sa pranuraktishware' means great love in God is Bhakti.
There is two man branch of Bhakti Yoga
Nirakar Brahma
Sakar Brahma
In Nirakar Brahma, we worship to the God as a creater without any face(charater) and in the form of super energy.
In the Sakar Brahma, we worship the charater(face) of the God.
Sakar Brahma has again two branch as follow:
Faminin energy: In this Bhakti take place towards energy form(Maa Durga and her various faces) and this is mostly popular in Tantra Yoga, also as a simple being without Tantra.
Masculin form of charater: This have also many branches. Shaivisam, Vaishnavism etc. Even in this category peoples worships to the other faces of the Vishnu(Krishna, Narayan, Ram, Narsimha, Jagannath etc.) and Shiva(Rudra, Kalbhairav, Natraj, Nilkanth, Pashupati, Mahaeev, Gaurikedareshwar, Rameshwar etc.) and other God(Hanuman, Lord Ganesh, Kartikeya, etc.) and Goddess(out of shakti or energy face such as Saraswati, Parvati, Narayani etc.)
There is one interesting and important theory. There is a question, to whom God will be listen first or he(God) will be run itself without care that he is the God? To his Bhakt he will run without care anythingy. If Bhakt call to the God then he just run to his Bhakt in the faces in which bhakt love him. There are two relationship with the God in Sakar Brahm. One is his direct characterstic face as a God an in otherone as a familier or friendly(sudama) relationship. Familier realation can be brother, father(Bhakt Prahlad, Markandeya), son(Yashoda, Devaki, Kausalya), daughter, sister, mother. Bhakti can be any faces in which you will like to see the God.
According to above Bhakti yoga can divided as following:
Das(son or servent): In this Yoga you worship to the God as a father or owner of itself. It is more purified form of Bhakti yoga. This is most popular form of Bhakti yoga. In this ego will be on lowest level as other form of devetion. Hanuma, Narad, Markandeya, Prahalad, Jesus, Chatanya Mahaparbhu, Shirdi Saibaba are the exmaple of this Bhakti Yoga.
Sakha(friend): In this you worship to the God as a friend, in this ego work as a balace form. This is not so popular form of Bhakti Yoga but in this form need to lot of understanding. In this yoga you get lot of balanced fun and free love towards God. Sudama, Arjuna, Kevat is the best example of this Bhakti Yoga.
Vatsalya(pure love form as being parent of God): This is very great form of Bhakti yoga and in this form you worship to the God as a his child face. Most popular child face is of Lord Krishna, God of love. Due to this reason, India they celebrate birthday of Lord Krishna(shri Krishna Janmastami). In this they get lot of happiness and love which is in the form of tears of happiness, tears of love and achievement. Shabari, Yashoda, Devaki, Janak, Dashrath are the example of this Bhakti Yoga.
Madhurya(pure love as a friend):In this form also we worship to the God as a friend gut not the shared friend. It means not husband or wife form. Just your own beloved. In this there is be subject of sensual organ but in the very purified form. Radha, Meerabai are the best example of this Bhakti Yoga.
Bhakt Prahlad says,
Shravan Kirtan vishnoh smaranam padsevanam I
Archanam chandanam dasyam sakhyamatmnivedanam II
Can get to God from listening(sound related to the God), Kirtan(singing text related to the God), Remembering to God, feeling in feet of God, worship, salutation, feeling to God as own owner, friendly feeling.
There are some additional practice to being success in the field of Bhakti Yog as following.
Patience(Tapa, or sacrifying sensual and physical comfort)
Santosh(Satisfaction)
Astha(Trust)
Satya(Speaking Truth)
Tyag (Sarifying of sensual subject)
Karuna(Compassion)
Swadhyay(Self analysis)
Ishwar Pranidha(Devotion)
Japa-Ajapa(Mantra singing, Bhajan and remembering always to him)
There is one time come when you forget all and you are very in deep with itself by singing bhajan and your mind is without any impurities some unique energy develop and this energy start to work on your important sleeping part of the brain and this energy will be enough to awake this part and you becomes Yogi. Near to the God.....Kashinath