Devotional service

The basic principle of devotional service is detachment from material activities and attachment to the transcendental service of the Lord. (Bhagavad-gita 15.1 purport).

Devotional service means mukti, freedom from material entanglement (Srimad-Bhagavatam 5.11.4 purport).

By absorbing our senses in activities centred around Krishna, we cultivate attachment to Krishna, which will gradually develop into love, and all our attachment to material activities will be forgotten.

Further reading: Srimad-Bhagavatam 9.4.18-20 or Bhagavad-gita 2.61 purport

Two main branches of devotional service

Pancaratrika-vidhi: Devotional service focused on or centred around Deity worship.

Bhagavata-vidhi: centred around hearing and chanting the Holy name and Preaching.

Bhagavata-vidhi is more important:

Both are important for cultivating Vaisnavism but comparatively speaking bhagavata-viddhi is more important than pancaratriki-viddhi.
By chanting the holy name of the Lord, one can reach the platform of love of Godhead.
To chant the holy name of the Lord, one need not depend upon other paraphernalia, for one can immediately get all the desired results of connecting or linking with the Supreme Personality of Godhead.
Chanting the holy names is sufficient for attaining perfection, pure love for God and returning back to Godhead.
Preaching makes one most dear to Krsna.
Preaching connects others to Krsna.
Without hearing, one will lose interest.

But Pancaratrika-vidhi is still essential:

Srila Jiva Gosvami says that although sankirtana is sufficient for the perfection of life, the arcana, or worship of the Deity in the temple, must continue in order that the devotees may stay clean and pure. (Srimad-Bhagavtam 6.3.25 purport).

To help free us from previous bad habits, material contamination, restlessness, and sense gratification.
To become clean and pure in habits.
For developing one's service attitude.
Theoretical book knowledge is insufficient for realisation; Deity worship gives practical engagement.
To attract people to the temple; supports the preaching.
Purity makes the preaching more effective.
Sri Chaitanya Mahaprabhu established sankirtana but He ordered the Goswamis to establish temples.

Therefore Both Are Required:

The Krishna conscious movement accepts both processes simultaneously and thus enables one to make steady progress on the path of realization of the Supreme Personality of Godhead. (Srimad-Bhagavatam 4.13.3 purport).

Bhagavata-marga will help the pancaratrika-marga, or process, and the pancaratrika process will help the Bhagavata process. Both together is helpful. (Srimad-Bhagavatam Lecture, 13 February 1971)

The Golden Rule of Bhakti

smartavyah satatam visnur
vismartavyo na jatucit
sarve vidhi-nisedhah syur
etayor eva kinkarah

Visnu should always be remembered and never forgotten at any time. All rules and prohibitions mentioned in the sastras should be servants of these two principles.
(Padma Purana)

Life is full of ups and downs. An inexperienced devotee will especially remember Krishna when he´s down, but a more experienced devotee also remembers to be thankful to Krsna and to take shelter of Him even when everything seems to be great.

Sadhana-bhakti

What is Sadhana?

What does the word sadhana mean? According to the Monier-Williams Sanskrit dictionary sadhana is:

The means to achieve an end; carrying out ; bringing about; completion

In his books, Srila Prabhupada describes sadhana-bhakti (or the means to achieve pure devotion) in the following ways:

Devotional service performed according to the rules and regulations.
Practice for the spiritual world.
The beginning stages of devotional service leading up to bhava-bhakti and then prema-bhakti
A means to awaken the dormant service instinct.

Two main categories or levels of Sadhana-bhakti:

Vaidhi-bhakti: regulated service performed out of obedience to the instructions of the spiritual master or the scriptures.
Raganuga-bhakti: service performed out of spontaneous attraction.

One can compare it to an automobile that needs to be pushed to get it going. Once it starts running, it moves under its own energy.

Therefore in the beginning, the newcomer in spiritual life must render devotional service under the guidance of a bona fide spiritual master according to the regulative principles mentioned in the revealed scriptures.