Srila Bhaktivinoda Thakura has elaborated on the Nine Angas of Bhakti In Jaiva-dharma Chapter 19 Prameya-Abhidheya-Tattva:
Sri Hari’s name is the life and soul of mantra. The rsis have added words such as namah (‘obeisances’) to sri-hari-nama, and disclosed its specific power. Sri-hari-nama by nature has nothing to do with this material world, whereas the jiva, because of various bodily designations provided by maya, is entrapped by objects consisting of dead matter. Consequently, in order to detach the jiva’s mind from sense objects, different principles of arcana have been established on the path of regulated devotional service (maryada-marga). It is essential for materialistic people to accept diksa. When one chants the Krishna mantra, siddha-sadhya-susiddhaari are not considered.
Initiation into the exclusive chanting of the Krishna mantra is extremely beneficial for the jiva, for of all the different mantras in the world, the Krishna-mantra is the most powerful. A bona fide disciple receives strength from Krishna immediately when a bona fide spiritual master initiates him into this mantra. After initiation, Gurudeva educates the inquiring disciple concerning the performance of arcana. Briefly, arcana-marga includes the observance of Sri Krishna’s Appearance Day, fasting in Karttika month, observing Ekadasi, taking bath in the month of Magha, and other such activities. One should also understand that one must certainly worship Krishna’s bhaktas as well as Krishna Himself on the path of arcana.
The sixth anga of vaidhi-bhakti is offering prayers and obeisances (vandanam). This is included as part of pada-seva and kirtana, but it is still considered a separate anga of bhakti. Namaskara itself is also called vandanam. Ekanga-namaskara and paying obeisances with eight parts of the body touching the ground (astanganamaskara) are two types of namaskara. It is considered offensive to offer obeisances with only one hand touching the ground; to offer obeisances when the body is covered with cloth, to offer obeisances behind the Deity; to offer prostrated obeisances with the body pointing directly towards the Deity, or with the right side towards the Deity and to offer obeisances in the garbha-mandira (Deity room).
Performing service (dasyam) is the seventh anga of bhakti. “I am Krishna’s servant” – this ego or conception of the self is dasyam, and bhajana performed with the sentiment of a servant is the topmost bhajana. Dasyam includes offering obeisances, reciting prayers, offering all of one’s activities, serving, keeping proper conduct, remembering and obeying orders (katha–sravanam).
The eighth anga of bhakti is serving as a friend (sakhyam), which includes the mood of kinship towards Krishna with the endeavors for His wellbeing. There are two kinds of sakhyam: friendship in vaidhi-bhakti and friendship in raganuga–bhakti, but Sri Prahlada’s verse refers to vaidhanga-sakhyam; for example, the feeling of sakhyam while serving the Deity is vaidha-sakhyam.
 Gurudeva will give initiation to his disciple after performing the process for purifying him of the four defects of siddha, sadhya, susiddha and ari (enemy). One may consult Hari-bhakti-vilasa, First Vilasa, Anuccheda 52- 103 regarding these four defects and their remedial measures. But in chanting the king of all mantras, the Krishna-mantra of eighteen letters (gopala -mantra), there is no need to consider these four defects, because the mantra is so powerful that these four defects are very insignificant in comparison. In Trailokya Sammohana-tantra, Mahadeva has said, astadasaksara mantram adhikrtya sri-sivenoktam na catra satrava doso varnesv adi-vicarana, and in Brhad-Gautamiya it is stated: siddha-sadhya-susiddhari-rupa natra vicarana, sarvesam siddhamantranam yato brahmaksaro manuh. Every single letter of this mantra is brahma.
 Raganuga-bhakti—devotional service following the spontaneous loving service of the inhabitants of Vrndavana.