What is actually the correct method to chant the Harekrishna Mahamantra? Like what we should follow before chanting of that mantra, and which direction we have to face while chanting the mantra, and how we should end the process of chanting this mantra?
According to the 'Kali-Santarana-Upanishad', the Mahamantra is mentioned as : Hare Rama Hare Rama ..Hare Hare/ Hare KrishNa Hare KrishNa .. Hare Hare//
punar narada¿ papraccha bhagavan ko 'sya vidhir iti | taµ hovåca nåsya vidhir iti |
sarvadå çucir açucir vå pa†han bråhmanah salokatåµ samîpatåµ sarûpatåµ såyujyam
eti | yadåsya ßo¥açakasya sårdha triko†ir japati tadå brahma-hatyåµ tarati |....
English Translation (of the relevant part): There is no rule to be followed to chant the Mahamantra for the brahmins. They chanting it in pure or impure state attains different forms of mukti like sAlokya, sAmipya, sAjujya etc getting freed from all sins. This Upanishad also says that chanting the maantra 'sArdha-Tri-koti-vAra' ie three crores and fifty lakh times in total is required to get the results.
It is a Veda-mantra and especially specified for the brahmins.So one view is that Mahaprabhu preached it by reversing the order making it chantable by all while keeping everything including the fruits unchanged.Other views say that He compiled it from the Agni-purAna and another from the BrahmAnda -purAna as hypothesised by Dr. Mahmanamavrata Brahmachari. In RadhA-tantra also the Mantra starts with 'Hare Krishna' by the way.According to Mahaprabhu also, no rule has to be followed for chanting the 'Hare Krishna' Mahamantra:
ihA hote sarva-siddhi hoibe sabAr/sarva-kshan balo ethe nAhi vidhi Aar// meaning: This [Mahamantra] will give you all what you want.Just chant it all the time and there is no other rule to be followed (Sri Chaitanya-BhAgavata).
In Sri Chaitanya CharitAmrita also He says
diksha-purascharyA vidhi apekshA nA kare/jihva-sparshe Achandal sabAre uddhAre// meaning that for chanting of the Mahamantra one does not need any initiation or 'purascharana'. Just uttering is enough to get liberation for all the castes.
So Mahaprabhu also makes it clear that no rule has to be followed at all to chant the Mahamantra.
Reference:MahAmantra-sankirtan,Sitaramdas Omkarnath,Omkarnath Rachanavali, Vol.14, page 264-311.
The entire Kali-Santarana-Upanishad can be downloaded from here.Those who think that the word 'Braahmana' is NOT there, may please check this.The one from which I quoted also contains 'Braahmanah' : https://freehindipustak.blogspot.com/2018/05/kalisantaran-upanishad-hindi-sanskrit.html