The Gita is very clear that one has to put effort by these three:
1. Karma Yoga: work and offer the fruits of action to the Lord and then offer the action itself to Him, be even-minded in success and failure
2. Dhyana Yoga: subdue the senses and the mind, concerntrate on the Lord by absorbing the mind and senses in the Lord, talk about the Lord always
3. Bhakti Yoga: serve the Lord who dwells in all the living beings, engage in the welfare of all living beings
When a person does these, the Lord, who abides in the heart, lights the lamp of Knowledge, destroys the darkness of ignorance and saves the person out of the ocean of Samsara. This is Jnana Yoga, which happens easily and almost automatically if the first three are done properly.
Here are some excerpts from the Gita, which indicate clearly the Way.
6.3: For the man who wants to attain concentration of mind, the path of action is the way. For the man who has attained concetration (yogaarooda), the path of inaction (contemplation) is the way (to proceed further to the Unmanifest).
6.4: One has said to have attained concentration when there is no attachment either to sense-objects or to actions and all worldly agenda (sankalpa) have been renounced.
6.28: The Yogi, freed from taint (of good and evil), constantly engaging the mind in contemplation, wth ease attains the infinite bliss of contact with Brahman, the Unmanifest.
6.29: With the heart concentrated by Yoga, with eye of evenness for all situations, he beholds the Self in all beings and all beings in the Self.
6.30: He who sees Me in all the things and sees all the things in Me, he never gets separated from Me, nor do I become separated from him.
6.31: He who being established in unity, worships Me who am dwelling in all beings, whatever his way of life, that Yogi abides in Me.
10.8: I am the origin of all, from Me everything evolves – thus thinking, the wise worship Me with loving consciousness.
10.9: With their minds wholly in Me, with their senses absorbed in Me, and always speaking of Me, they are satisfied and delighted.
10.10: To them, ever steadfast and serving Me with affection, I give that Buddhi Yoga by which they come to Me.
10.11: Out of mere compassion for them, I, abiding in their hearts, destroy the darkness (in them) born of Ignorance, by the luminous lamp of Knowledge.
12.3,4: They who have subdued all the senses, are even-minded everywhere, are engaged in the welfare of all beings, when they worship me as the Unmanifested, reach Me.
12.5: Great is their difficulty whose minds are set on the Unmanifested, for the goal of the Unmanifested is very hard for the embodied to reach.
12.6,7: Those who worship Me, resigning all actions in Me, regarding Me as the Supreme Goal, meditating on Me with singleminded Yoga, to these whose mind is set on Me, verily, I become before long, Partha, the Saviour out of the ocean of the mortal Samsara.
Thus, the Lord says, do these three:
(1) subdue all the senses and the mind (by self-control and meditation)
(2) be even-minded everywhere (in success/failure, pleasure/pain, fame/infamy)
(3) engage in the welfare of all beings
If we do these three, He will take care of the rest. So simple.