Śrīman Mahāprabhu instructs us in chanting the dual Rādhā-Kṛṣṇa name, which consists of thirty-two syllables, sixteen words and eight joints. This mantra is called āhvanātmaka nāma, which means that one calls out to the Lord with it (it is not just for silent meditation, like most other mantras), or tāraka brahma nāma (the transcendental saviour-name). 

The best way to enter into the nikuñja mandira and to serve Śrī Rādhikā there is to congregationally chant this hare Kṛṣṇa-sambodhanātmaka nāma (a mantra simply consisting of addresses). 

Śrīla Sanātana Gosvāmī says:  

nāma saṅkīrtanaṁ proktaṁ Kṛṣṇasya prema sampadi; baliṣṭhaṁ sādhanaṁ proktaṁ paramākarṣa mantravat  
(Bṛhad Bhāgavatāmṛta 2.3.164)   

“The Śrī Kṛṣṇa-nāma-saṅkīrtana is the most powerful means to attain the treasure of love of Kṛṣṇa. It is like a most attractive mantra.” 

The Lord will personally appear before anyone who chants this nāma sankīrtana with an innocent and eager heart. Srī nāma saṅkīrtana will attract the most precious thing, just like a perfect mantra.  

tad eva manyate bhakteḥ phalaṁ tad rasikair janaiḥ bhagavat prema sampattau sadaivāvyabhicārataḥ   

“For this reason the bhakti-rasikas (the relishers of devotion) have defined it as the ‘fruit of devotion’. It is always the most faultless way to attain the treasure of prema.” (idem 2.3.165) 

Someone may ask here: “I thought that the goal of sādhana-bhakti was prema, and that nāma-saṅkīrtana was also a kind of sādhana. How can it be called the goal then here?” 

The answer to that is: “It’s true, nāma saṅkīrtana brings the treasure of prema and because the appearance of prema is certain through the practice of nāma saṅkīrtana it is also called the fruit or result of devotional practice. There’s never any exception to that rule, and therefore the saints call nāma saṅkīrtana the fruit of devotional practice. Along with smaraṇa, nāma saṅkīrtana swiftly enables the practising devotee to relish the sweetness of Śrī-Śrī Rādhā and Kṛṣṇa.

– Srila Ananta das Babaji