PuruSottamachAryA lists three stages of jNAna. These are SravaNa (hearing the texts), manana (reflection and discussion) and nidhidhyAsana (vision of the lord). When kRRiShna gave jNAna to arjuna (gIta 18.64), he said
shRRiNu me paramaM vachaH... tato vakShyAmi te hitam
Hear this supreme instruction from me, for it is for your benefit
GIta also says (13.26):
shrutvAnyebhya upAsate te ’pi chAtitaranty eva mRRityuM shruti-parAyaNAH
By hearing from others, they begin to worship: because they are inclined to the process of hearing, they also certainly overcome death.
GIta 10.18 also gives a good example of how we should desire to listen for attaining jNAna. On manana, muNDaka upaniSad (3.2.6) says about liberated souls:
vedAntavij~nAnasunishchitArthAH
Having without doubt well ascertained the significance of the knowledge of Vedanta
NidhydhyAsana, also called brahmavidya, has 32 types according to upaniSads
As well as these three stages of jNAna itself, there are certain qualifications or conditions for attaining it. You can read about the nimbArka description of them here. Not all of them are absolutely necessary: one can begin jNAna by just one of them. Following our obligatory actions (according to our state in life and dharmasUtra) is an auxiliary, so brahmasUtra 3.4.26 says
sarvApekShA cha yaj~nAdishruter ashvavat
(rough meaning) all religious activities such as sacrifices as well are necessary for knowledge
In describing the personal qualities needed to begin jNAna, shvetAshvatarupaniShad (6.22-23) says
nAprashAntAya dAtavyaM nAputrAyAshiShyAya vA punaH. yasya deve parA bhaktir yathA deve tathA gurau, tasyaite kathitA hy,
[Vedanta] should not be given to one not tranquil, nor again to one who is not a son or a pupil. To him who has bhakti for God, and for his guru as for God, have these matters been declared.
So, Vedanta and jNAna can only be given by a spiritual father (guru), or bodily father. Bhakti is a requirement for it. BrahmasUtra 3.4.27 summarises how bRRihadAraNyakaupaniShad (4.4.23) gives some more conditions for beginning jNAna marga:
tasmAdevaMvichChAnto dAnta uparatastitikshuH samAhito bhUtvAtmanyevAtmAnaM pashyati
he who... having become calm, self-restrained, indifferent, patient and collected, should see the self in the self alone
Devotional service is also an auxiliary to jNAna, especially for those without varna.
In conclusion, there are three auxiliaries to jNAna marga: three or six obligations (depending on varna), eight personal qualities (tranquil, bhakti, son or pupil, calm, self-restrained, indifferent, patient and collected), and six general requirements (devotional service in its many forms, deep learning, childlike simplicity, unostentatiousness, profound thoughtfulness and silence). In total this leaves 17 or 20 part auxiliaries to jNAna marga. The three stages are hearing, reflection and vision of the lord.