Select an Ishta Devata either Siva, Krishna, Rama, Vishnu, Dattatreya, Gayatri or Sakti according to the advice of your Guru, or your own inclination or on consultation with a good astrologer who will name the Deity according to your planetary influence. Get the proper Mantra also OM Namah Sivaya, or OM Namo Bhagavate Vasudevaya, OM Sri Ram Jaya Ram Jaya Jaya Ram, or OM Namo Narayanaya. Keep a photo of your Ishtam in front of you in the meditation room. For 6 months, do Trataka on the picture. See the picture carefully with concentration for half an hour without winking till tears flow profusely.
Study constantly the Bhagavata, the Ramayana, Narada Bhakti Sutras and Sandilya Sutras. Live for one year in Ayodhya, Mathura, Pandarpur or Nadia, Bengal. Pass through the course of Nava Vidha Bhakti, Sravana, Smarana, Kirtana, Vandana, Archana, Pada Sevana, Sakhya, Dasya, Atmanivedana. Repeat your Guru Mantra constantly, all throughout the 24 hours. Have sleep for 3 hours. Select a Bhava suitable for you, either Madhurya, Sakhya, Dasya or Vatsalya. Make ungrudging, unreserved, true, perfect self-surrender to God. Do Antarika prayer from the bottom of your heart. Prayer can move mountains. Prayer can reach a realm wherein reason can hardly enter.
Have Eka Nishtha, devotion to one ideal. The Bhakti must be Ananya, Avyabhicharini (unwavering, one-pointed, single-minded devotion). Develop slowly Anurag, Prem, Preeti, Viraha (pain of separation from God), Bhava, Maha Bhava. In Maha Bhava, the devotee is unconscious of his body and the world and is absolutely merged in God. From Apara or lower Bhakti, the devotee passes on to Para or Abheda Bhakti. A devotee gets Krama Mukti or progressive emancipation after passing through Salokya, Sameepya, Sarupya and Sayujya Mukti.
"Dadami Buddhiyogam Tam Yena Mam Upayanti Te: I give the Yoga of discrimination by which they come unto Me."-Gita, X, 10.
After enjoying the lower Mukti, a devotee finally attains Kaivalya Moksha, the same state as that of a Jnani. An earnest Sadhaka with Utsaha (perseverance) can realise within 2 or 3 years. I assure you emphatically. I assure you sincerely and boldly. Make a sincere effort, and watch the results.
Follow Lord Krishna's instructions in the Gita, as described in the terms 'MACCHITTA', 'YUKTA', 'MATPARA'.