There are always rogues and thieves in human society, and as soon as a weak government is unable to execute its duties, these rogues and thieves come out to do their business. Thus the entire society becomes a hell unfit for gentlemen to live in. There is an immediate need for a good government – a government by the people, with Krishna consciousness. Unless the masses of people become Krishna conscious, they cannot be good men. The Krishna consciousness movement that Sri Chaitanya Mahaprabhu started by chanting the Hare Krishna maha-mantra still has its potency. Therefore people should understand it seriously and scientifically and spread it all over the world.
His Divine Grace A. C. Bhaktivedanta Swami Prabhupada
Sri Chaitanya-charitamrita, Adi-lila 17.141, Purport

Sri Krishna Himself helps us in finding the really good preceptor in two ways. In the first place He instructs us regarding the character and functions of a great preceptor through the revealed shastras. In the second place He Himself sends to us the good preceptor at the right moment when we are at all likely to benefit by his instructions.
Srila Bhaktisiddhanta Sarasvati Thakura
“Initiation into Spiritual Life,” Sajjana-toshani, Vol. 16, No. 1

One who strongly desires great bliss should do japa of Lord Hari’s name, which is topmost, meditate on the name, sing the name continuously, and do kirtana of the name.

Remembering Vishnu destroys sin, but that is accomplished with great endeavor. But doing kirtana, simply by vibrating the lips, is better than remembrance.

The reason why the Lord, who is merciful to the fallen, did not reveal the glory of kirtana in other yugas, when the people were capable of other sadhanas like meditation, is that they thought that kirtana was not very significant as a sadhana, being mere moving of the tongue and lips, and thus had no faith in it.
Srila Jiva Goswami
Bhakti-sandarbha, Anuccheda 272

Offending the guru is billions of times worse than offending the Lord. But denying scriptural knowledge and not accepting the authority of the Vedas is ten million times worse than offending the guru.
Vyasa-gita of the Kurma Purana

Of the different processes recommended for disentanglement from material life, the one personally explained and accepted by the Supreme Personality of Godhead should be considered all-perfect. That process is the performance of duties by which love for the Supreme Lord develops.
Sri Prahlada Maharaja
Srimad-Bhagavatam 7.7.29