First Srila Bhaktivinoda quotes SB 11.18.42] grhino bhuta-raksejya, "The main duties of a householder are to give shelter to all living entities and perform sacrifice."
What is proper occupation? To know this, one should see the behavior of Sri Caitanya Mahaprabhu's followers. As far as possible I will try to briefly compile them in this essay. First I will write about the behavior and occupation of the grhastha, as found in the character of Sri Caitanya Mahaprabhu and His devotees.
* As a support for his devotional service, a householder should find a suitable wife. (CC Adi 15.26-27)
* While maintaining religious family life with one's wife, sons and daughters born in the form of Krsna's servants and maidservants, to nourish them is called maintaining the family. In these activities there is a need for piously accumulating wealth. (CB Antya 5.41, CC Madhya 15.96)
* One must be educated at a proper age. But he should not study atheistic literatures. (CB Adi 12.49, Madhya 9.241-242)
* Serving guests is the principal duty of a grhastha--this is the Lord's instruction. (CB Adi 14.21, 26)
* A grhastha should act with simplicity in his dealings with people; he should not allow any kind of cheating or duplicity in his heart. (CB Adi 14.142)
* It is the principal duty of a grhastha to serve superior persons. (CC Adi 15.21)
* A householder should take the principles of renunciation to heart; but he should not dress as a renunciant. (CC Madhya 16.237-239)
* A householder is dutybound to work for the benefit of everyone. (CC Adi 9.41, 7.92)
* A householder should fully depend on the will of the Lord in all his activities. (CB Madhya 28.55)
* A householder should cautiously give up the association of nondevotees, women, and uxorious people. (CC Madhya 22.87)
* By following his prescribed duties a grhastha Vaisnava should accumulate wealth for his maintenance. He should not accumulate wealth by sinful means. (CB Antya 5.685-688)
* A householder should not hanker for another's wife or prostitutes. (CC Madhya 9.227-228)
* There is no difference between smartas and Vaisnavas regarding following the codes of religion. (CB Antya 9.388-389)
* It is the duty of a grhastha to constantly chant the holy names of the Lord and serve the Vaisnavas and the Lord with the help of his relatives and by the wealth he has earned through his pious life. Regarding serving the Vaisnavas, one should know that there are three types of nonduplicitous devotees. SErving such Vaisnavas is called vaisnava-seva. (CC Madhya 15.104)
* There is no need to gather many Vaisnavas by invitation [for prasada --VGD]. Whenever a Vaisnava comes for any purpose he should be properly served with care. By gathering many Vaisnavas, one may commit offenses. (CC Madhya 15.198)
* It is the duty of the grhastha Vaisnava to show mercy on the poor and the fallen. (CC Antya 3.238)
* A grhastha Vaisnava should not desire to give up his body merely out of some sentiment or anger. (CC Antya 4.57)
* There is no consideration of superior or inferior status due to social position in regard to worshipping Krsna. In worldly occupations there are different activities according to the different social divisions, which are due to superior and inferior grades of intelligence. There are no such distinctions in the process of devotional service. (CC Antya 4.66-67, 5.84)
* A grhastha Vaisnava should feel satisfied with whatever food and clothing he gets without difficulty. (CB Antya 4.293)
* A grhastha Vaisnava should perform devotional service with undeviated attention, knowing Krsna as the Lord of all. He should not disrespect the demigods worshipped by the smarta-sampradaya. (CB Antya 2.243)
* It is the duty of a grhastha to work for the benefit of others even by giving up his own self-interest. (CB Antya 3.365)
* A grhastha Vaisnava should respect and worship tulasi. (CB Antya 8.159-160)
* A householder with devotion is glorious, while a householder without devotion is insignificant. Whatever social dealings a householder has to perform should be done while taking shelter of the holy name of Krsna. (CC Antya 16.6-7)
* Everyone is prohibited from corrupt earning or spending, and workers are prohibited from accepting bribes. (CC Antya 9.90, 142-144)
* A grhastha should accept a spiritual master who is full of devotion and of pure character. (CB Madhya 21.65)
* A householder should be particularly careful not to commit offenses against the Vaisnavas. (CB Madhya 22.33)
* Serving devotees is a householder's main duty. (CC Antya 16.57, 60)
* In the SB 11.20.27-28 Lord Krsna describes how a householder should act until his natural propensity for enjoying sense objects is overcome and he fully attains the characteristics of a pure devotee: "Having awakened faith in the narrations of My glories, being disgusted with all material activities, knowing that all sense gratification leads to misery, but still being unable to renounce all sense enjoyment, My devotee remains happy and worships Me with great faith and conviction. Even though he is sometimes engaged in sense enjoyment, My devotee knows that all sense gratification leads to a miserable result, and he sincerely repents such activities."
* When a householder has faith, he should take initiation into the chanting of the Hare Krsna maha-mantra. (CC Madhya 22.64)
* A grhastha Vaisnava must gradually acquire all the qualities mentioned in the Caitanya Caritamrta (Madhya 22.78.80): "Devotees are always merciful, humble, truthful, equal to all, faultless, magnanimous, mild and clean. They are without material possessions, and they perform welfare work for everyone. They are peaceful, surrendered to Krsna, and desireless. They are indifferent to material acquisitions and fixed in devotional service. They completely control the six bad qualities---lust, anger, greed, and so forth. They eat only as much as required, and they are not inebriated. They are respectful, grave, compassionate, and without false prestige. They are friendly, poetic, expert and silent."
* A grhastha Vaisnava should be eager to associate with advanced devotees. (CC Madhya 22.83)
* Out of all the processes of devotional service, one should give earnest attention to the five limbs mentioned in Caitanya-caritamrta (Madhya 22.128-129): "One should associate with devotees, chant the holy name of the Lord, hear Srimad Bhagavatam, reside at Mathura, and worship the Deity with faith and veneration. These five limbs of devotional service are the best of all. Even a slight performance of these five awakens love for Krsna."
* A grhastha Vaisnava should not endeavor for any knowledge or renunciation other than knowledge of one's relationship with the Lord in devotional service and renunciation born from devotional service. If one begins the worship of Krsna with special care and eagerness, then he achieves all auspiciousness. (CC Madhya 22.145)
* A grhastha Vaisnava should constantly chant the holy names while carefully giving up the ten offenses. (CC Antya 4.70-71)
* A householder should accept pure devotional service that is not based simply on religious sentiments. (CB Madhya 23.41)
* The mood of servitude is proper for a living entity, and the mood of being lord is detrimental. (CB Madhya 23.480, 482)
* A grhastha Vaisnava should model his character after that of Lord Caitanya and His followers. A householder should follow the ways of life and obtain his means of livelihood as exhibited by Lord Caitanya and His followers. If one desires Krsna in all his activities, then those activities are auspicious. By endeavoring to gratify one's senses and attain irrelevant fruits, one becomes a materialist... Srila Ramananda Raya, Sri Pundarika Vidyanidhi, Sri Srivasa Pandita, Sri Sivananda Sena, Sri Satyaraja Khan, and Sri Advaita Prabhu were all grhasthas and have shown us the way of faultless living. The difference between a householder and a renunciate is due to their different means of livelihood. If the home is favorable for a devotee's devotional service, he then becomes eligible to leave home. At that time the detachment he develops for his house through his devotional service is accepted. For this reason, Srivasa Pandita did not leave home. For this reason, Svarupa Damodara took sannyasa. All genuine devotees have remained either at home or in the forest due to this consideration. Whoever has left home due to this consideration is called a genuine renunciate. He is always careful to not commit offenses against the holy name.