Lord Krishna presents bhakti yoga in five levels.  The fifth level is jñāna yoga and that is the highest level of bhakti yoga.  The lord in jñāna is nirguna eeswara.  The worship of nirguna eeswara is unique, and it is not a physical worship because nirguna eeswara does not have a physical form.  So the worship is in the form study and inquiry of nirguna eeswara.  The inquiry consisting of sravanam, mananam nidhithyasanam.   jñāna yoga form of worship is presented in verses 3, 4 and 5.  The technical word for jñāna yoga aksharobasanam.  Lord Krishna admits jñāna yoga is difficult because:

1. Nirguna brahman is not available unobjectifiable and inconceivable.  It can be only received in one form only and that is in the form of myself. 
2. Requires lot of qualifications like viveka, vairāgyam etc. 

Since jñāna yoga is very difficult, people follow simpler yoga like bhakti yoga, karma yoga etc.  For moksha, many paths are not available, and scriptures clearly says jñānam is the only path. If darkness is the problem, the only solution is to bring light.  All other acts like sweeping the floor, chanting slokas etc. will not remove darkness.  Ignorance goes away only by jñānam or knowledge.  You can get knowledge in any field only by inquiry and the relevant study.   That should be extended to jñānam.  If jñāna yoga is difficult, make it is easy, by preparing and qualifying for jñāna yoga.  Jñāna yoga is difficult for unprepared person and easy for a prepared person.   

Verses 6 and 7

Keeping Me as the primary goal and dedicating all actions unto Me, some devotees worship, mediating upon Me with undivided attention.  For them, whose minds are set on Me, I shall soon become the savior from the ocean of samsara, which is best with death, Oh Arjuna.

Those who find jñāna yoga to be difficult can practice saguna brahma upasana, meditating up on eeswara with attributes.  Saguna brahman can be:

1. Viśvarũpa saguna brahman, as described in the 11^th Chapter.  Dedicate all actions to the Lord.  Dedication is the attitude that after I complete my action, I will get a karma palam as per the laws of karma. I will accept the resulting karma palam, committing to the goal of nirguna eeswara.  This will make  them qualified for the fifth step of nirguna eeswara bhakti. 
2. Ishta devata brahman

Verse 8

Fix the mind on Me alone.  Fix the intellect on Me alone.  Thereafter you will dwell in Me alone.  There is no doubt.

In this stage, fix the emotional mind in viśvarũpa lord and the intellectual mind should be convinced of viśvarũpa eeswara as the world.  Akasha, vayu, agni all are eeswara.  The glory of viśvarũpa bhakti is I am never away from eeswara.  This should be the conviction born out of scriptural study.  If not convinced, continue the study until you are convinced of viśvarũpa eeswara. 

Verse 9

If you are not able to fix the mind firmly on Me, then seek to attain Me by means of abyāsaḥ yoga, Oh Arjuna!

If you are not able to come to viśvarũpa eeswara, come to eka roopa eeswara or Ishta devata upasana.  Choose any particular form or any particular form of relationship – like a father, mother or friend.  Ishta devata bhakti can be formed by dwelling on purana paryanāṃ.   Krishna calls this abyāsaḥ yoga.