Bhagavad Gita Verse 34, Chapter 4

tadviddhi pranipaatena pariprashnena sevayaa |
upadekshyanti te jnyaanam jnyaaninastattvadarshinaha || 34 || 
 
Know that by complete surrender, inquiry and service, you will receive instruction from those who have gained knowledge through direct realization of the eternal essence.
 
tat : that
viddhi : know
pranipaatena : surrender to the feet
pariprashnena : inquiry
sevayaa : service
upadekshyanti : will instruct
te : they
jnyaanam : knowledge
jnyaaninaha : those who have knowledge
tattvadarshinaha : through direct realization of the eternal essence
 
In the previous shloka, Shri Krishna spoke about the realization of the eternal essence that is obtained through the sacrifice of knowledge. Here, he describes the method through which we should go about pursuing that knowledge.
 
Shri Krishna says that we should begin by approaching a teacher who has two key qualities. One, he should be a tattva-darshinaha. He should have realized the eternal essence himself first-hand. Second, he should be a jnyaaninaha, one who knows the technique of communicating this knowledge. Both qualities are essential and complementary. One without the other will not work.
 
Having approached the teacher, we should first completely surrender ourselves to him and accept him as our teacher. If we don't do so then our ego comes into the mix and disrupts everything. The teachings will have no impact if such a thing occurs. We see this type of behaviour when someone approaches a teacher and ends up using that meeting to boast about one's own knowledge rather than surrender to the teacher.
 
Next, we should have a thirst for inquiry about the eternal essence, which will be reflected by the questions we ask the teacher. Questions like: Who am I? How do I free myself of bondage? This is what the teacher should be able to answer. All our scriptures including the Upanishads, the Gita and the Bhagavatam are a dialogue between a teacher and student. Furthermore, we should not question about worldly matters like should I get married, should I take this job and so on. Liberation should be top priority.
 
Finally, we should continue building a relationship with the teacher through serving him. This will foster humility in us. It will also build a better connection and tuning between the teacher and the student. In the Gita, both Arjuna and Dhritaraashtra heard the Gita, but only Arjuna truly understood it. This is because Arjuna was in tune with Shri Krishna and Dhritaraashtra was not. Also, there is absolutely no room for a transactional or "coaching class" relationship between the teacher and student. Service is the only way.
 
Even Sant Jnyaaneshwar gained knowledge by serving his guru Nivruttinaath. He says "yogiraaja vinavane mana aale vo maaye" which means "I gained realization by serving my guru yogiraaja Nivruttinaatha".