Accept only a pure devotee as guru

"He who imparts wrong teachings and he who receives them are both destined for hell. One who has accepted teachings and conclusions outside the line of pure bhakti has wasted his life. How then can such a person become a spiritual master? How can he save other conditioned souls? He himself is in illusion and is therefore an imperfect being, so how can he bring good fortune to others? One must understand that a pure devotee is not an ordinary soul. The scriptures declare that he is the most eligible to be a spiritual master.

The guru principle

"The diksa-guru and the siksa-guru are both intimate servitors of Lord Krsna. They are eternally situated in the Vraja mood of service; they are manifestations of Lord Krsna's energy. Never make the mistake of judging the guru as an ordinary mortal. The spiritual master is the representative of Lord Krsna's potencies, sent by the Lord as the eternal master of the disciples.

The body is a computer/machine that needs an operator in order to be of value; and the unique nature of each and every body is that it is basically a private computer/machine. It is almost impossible for one person to use someone else’s computer/machine. I can’t operate your body and you can’t operate mine.
Chris Butler Speaks

He must always be worshipped as an eternal associate of the Supreme Lord, nourished by the Lord's superior spiritual potency. However, one must never consider the spiritual master to be the Supreme Lord; this is mayavadi philosophy, not in line with the pure Vaisnava conclusions. The Vaisnava devotees are very wary of such misinterpretations, for the mayavadi whirlpool of word jugglery is indeed contaminating to the mind and heart. The spiritual master must always be worshipped according to the scriptural conclusions; when properly executed, these practices result in self-realization.

Guru-puja and respecting the spiritual master

"The spiritual master is to be worshipped first; only then may one worship Lord Krsna. The spiritual master should be offered different paraphernalia like a nice seat, shoes, foot bath, cloth, etc.; then with the spiritual master's permission one may worship the Deities of Sri-Sri Radha and Krsna. Food should be first offered to the Deities and then offered to the spiritual master, then