Benefits of Worshiping Tulasee
Although we can never fully describe the glories of Tulasee Devee. She is an eternal associate of Lord Krishn. The scriptures give us a hint of the value of worshiping her. The following list comes from the Padm Puraan.
--Tulasee is the essence of all devotional activities.
--The leaves, flowers, roots, bark, branches, trunk, and shade of Tulasee are all spiritual.
--One who applies the paste of Tulasee wood to the Deity of Krishn with devotion will always live close to Krishn.
--One who puts mud from the base of the Tulasee tree on his body and worships Krishn gets the results of one hundred days worship each day.
--One who offers a Tulasee flowers (Manjaree) to Lord Krishn gets the benefit of offering all other varieties of flowers, and he goes to the abode of Krishn.
--One who sees or comes near a house or garden where the Tulasee plant is present gets rid of all his sinful reactions, including that of killing a Braahman.
--Lord Krishn happily lives in the house, town, or forest where Tulasee Devee is present.
--A house where Tulasee Devee is present, never falls on bad times, and it becomes purer than all holy places.
--The fragrance of Tulasee Devee purifies all who smell it.
--Lord Krishn and all the demigods live in a house where mud from the base of the Tulasee tree is found.
--Without Tulasee leaves, Lord Krishn does not like to accept flowers, food, or sandalwood paste.
--One who worships Lord Krishn daily with Tulasee leaves attains the results of all kinds of austerity, charity, and sacrifice. In fact, he has no other duties to perform, and he has realized the essence of the scriptures.
--One who puts Tulasee leaves, that have been offered to Lord Krishn, into his mouth or on his head attains Lord Krishna's abode.
--In Kali Yug, one who worships, remembers, plants, keeps, or performs Keertan before Tulasee burns up all sinful reactions and quickly attains Lord Krishn's abode.
--One who worships Lord Krishn with Tulasee leaves releases all his ancestors from the realm of birth and death.
--One who remembers the glories of Tulasee or tells others about them will never take birth again.

The Worship of Tulasee Devee
For devotees aspiring to enter the eternal realm of Vrindaa Van, service to Vrindaa Devee is essential. Srila Prabhupada stressed this by making Tulasee Poojaa a daily part of morning program. Tulasee Devee is an expansion of Vrindaa Devee in this world. Every morning pray to Vrindaa Devee :

"ye tomaar sharan loy, taaraa vaanchhaa poorn hoy, kripaa kori koro taare Vrindaa Van Vaasee"
"Whoever takes shelter of you, all his desires are fulfilled and by your mercy he becomes a resident of Vrindaavan."

Tulasee Devee is worshiped in the morning, after Mangal Aaratee, when all the devotees should attend to her worship and circumambulation. First, obeisance are offered to Tulasee Devee with the Tulasee Pranaam Mantra. Following, the Tulasee Poojaa, Keertan song is sung while Tulasee Devee is offered incense, a ghee lamp, and flowers. When the song is finished, the assembled devotees circumambulate Tulasee Devee four times, offering her water. During the circumambulation the following Mantra is chanted ;
yani kani cha paapaani brahm hatyaadi kaani cha, tani tani pranashyanti pradakshinaah pade pade.
Finally, we again offer obeisance with the Tulasee Pranaam Mantra.

Lectures from Srila Prabhupada
Tulasee leaf is very, very dear to Vishnu. All Vishnu Tattwa Deities require profusely Tulasee leaves. Lord Vishnu likes garland of Tulasee leaves. Tulasee leaves mixed with sandalwood pulp and placed on the lotus feet of the Lord is the topmost worship. But we must be very careful that Tulasee leaves cannot be placed on the feet of anyone else except Lord Vishnu and His different forms. Tulasee leaves cannot be placed even on the lotus feet of Raadhaa Raanee or on the lotus feet of the Spiritual Master. It is entirely reserved for being placed on the lotus feet of Krishn. We can place, however, Tulasee leaves in the hands of Raadhaa Raanee for being placed on the lotus feet of Krishna. [April 7, 1970]

Tulasee Devee is a pure devotee of Krishn and she should be treated with the same respect given to all Krishn's pure devotees. Simply by worshiping her faithfully, a devotee can get himself free from all material miseries. In the Nectar of Devotion I have given two verses from the Skand Puraan, one of which is: "Tulasee is auspicious in all respects. Simply by seeing, simply by touching, simply by remembering, simply by praying to, simply by bowing before, simply by hearing about, or simply by sowing the tree, there is always auspiciousness. Anyone who comes in touch with the Tulasee tree in the above mentioned ways lives eternally in the Vaikunth world." [January 6, 1972]

The following list was compiled from scriptures and from Srila Prabhupada's instructions.
--Tulasee's body is spiritual. Although Tulasee appears as many individual trees, she is one person, and she comes wherever she sees devotion to Krishn.
--Every morning devotees should water and pray to Tulasee Devee and circumambulate her three times.
--Worship Tulasee with nice food, flowers, incense, a ghee lamp, and other traditional articles of worship.
--Protect the delicate Tulasee seedlings from birds and insects. It is an offense to turn the seedlings back into the soil.
--In places where Tulasee cannot survive the winters, when planted in the ground, provides a suitable house for her.
--Every day provide Tulasee fresh air, water (as needed be careful not to water too much), and sunshine (or plant lights).
--Neglecting to care for or water Tulasee properly is a great offense. Do everything carefully.

Pick only the leaves that grow next to the Manjaree (flowers) and the leaves that are ready to drop (they will turn a pale color) not the new, green ones. Pick the Manjaree as soon as they blossom. Avoid letting them go to seed, which takes much energy from the plant that can be used to make more leaves and flowers for Krishn's service. Pick the leaves one at a time with your fingertips. Don't shake or stroke the branch and damage healthy leaves. Pick with care and attention. Avoid using cutting tools.

Never cut or prune Tulasee Devee. This is a great offense. Remove dead branches if absolutely necessary. If branches obstruct a passageway, tie them back, but don't cut them. Pick Tulasee leaves and flowers in the morning, never at night (from sunset to sunrise).

Never use chemical sprays on Tulasee. Collect leaves once in the morning for worshiping Krishn and for putting on the plates of food to be offered to Him. Put at least one leaf on each preparation. Never pick Tulasee leaves for any other purpose than to offer to the Lord.

Krishn accepts even dry Tulasee leaves. Tulasee wood (taken after a plant has fully dried naturally) can be used to carve worship paraphernalia, such as beads. Place leftover Tulasee wood within the earth. Never use Tulasee leaves or flowers to make teas or juices, even after they've been offered to Krishn. It is a great offense to cook or heat Tulasee, or to use her for mundane purposes, such as medicines and ointments.

--Never cut down or pull up living Tulasee plants. This is a great offense.
--Avoid stepping on Tulasee Devee's shadow.
--Tulasee is very, very dear to the Lord, therefore, most important is to serve her with love and devotion.
--When a Tulasee plant dies, it is immersed into a holy river, pond or lake with the same reverence as is shown to an image of god at immersion.
--Tulasee should never be grown from seed, instead one should bring a plant from a house or a temple and plant it in his house.

Tulasee As Naivedya
Among all articles which are offered to the Vishnu, Tulasee is most highly praised. Therefore one may perform perfect worship of the Lord by simply offering pure water and Tulasee leaves (Raghunatha das Goswami, Adwait Aachaarya). According to the Garud Puraan, Tulasee must always be offered on the Naivedya to Vishnu. Poojaa, bathing and offering of food and drink performed without Tulasee cannot be considered as Poojaa, bathing and offering to the Vishnu. Vishnu does not accept anything without Tulasee. --Brihad Naaradeeya Puraan

During the Poojaa, one should offer Tulasee leaves to the Lord's feet. Tulasee garlands may also be offered around His neck. In Badaree Naath temple Tulasee leaves garland is offered to the Deity. Some say that Gandh, flowers and Tulasee should be offered at least three times, washing the hands each time before offering. The article is offered from the right hand, while the left hand touches the right arm. Some say that offering eight Tulasee leaves is best.

Plucking Tulasee Leaves
--One should be clean before touching or plucking Tulasee. One who picks Tulasee without having bathed and then performs worship, is an offender, and all his activities becomes useless. --Vaayu Puraan
--Tulasee should not be plucked on Dwaadashee. The Vaishnav should never pick Tulasee leaves on Dwaadashee Tithi. --Vishnu Dharmottar
--One should always pluck the leaves with the right hand, holding the branch in the left hand, being careful not to break the branches. If when picking Tulasee leaves, one breaks the branches, Vishnu feels pain in His heart. One should clap the hands three times before picking Tulasee leaf and pick in such a way that the branches do not shake. --Vishnu Smriti
--One should say while plucking leaves for worship :
tulasya amrit janmasi sadaa twa keshav priya, keshavaarthe vichinvaami varad bhav shobhane
twad ang sambhavaih patraih poojayaami yathaa harim, tathaa kuru pavitraangee kalau mal vinaashinee
Oh Tulasee, born from the ocean of nectar, you are eternally the dear most to Keshav. For His worship I now pluck you. Please bestow blessings on me. Oh Tulasee, being pure in body and the destroyer of the sins of Kali Yug, I will worship the Lord using leaves coming from your body. You should make that worship successful.

--If Tulasee is unavailable, one may touch Tulasee wood to the Lord's body as an offering of Tulasee. If wood is unavailable one should chant the name of Tulasee and perform the Poojaa meditating on her presence. (etat Tulasee patram shree Krishnaaya namah)
--If one offers Tulasee to anyone other than Hari, that sin is equal to killing a Braahman or a cow, or having sex with ones Guru's wife.

Tulasee Prasaad may be offered to the hand of Shakti and Jeev Tattwa, and un-offered Tulasee may be offered to their hand for offering to Krishn. If Bhog (not Mahaa-Prasaadam) is offered to Shakti or Jeev Tattwa as Naivedya, Tulasee may be placed on the Naivedya, since, being devotees of Vishnu they always offer the Naivedya to Krishn before taking it themselves. All Vishnu Tattwa deities require profuse Tulasee leaves.

Caring for Tulasee
No sprays can be used on Yulasee, not at all. The best thing is to simply daily water Tulasee Devee and keep her clean. Nothing else is required. --Letter from Srila Prabhupada - July 26, l975, Los Angeles

You may take care of the Tulasee plants in the following way. From 15 April to 15 June is the best season for growing this plant. The seedlings come out at this time, so the whole spot if possible may be covered by some net because at the seedling stage,  the plants being very delicate, are prone to be eaten up by the sparrows, so we have to give a little protection from attack of the sparrows. All the devotees should pour water at least once in the morning before taking Prasaadam. The watering may not be in a very large in quantity, but it should be poured just to keep the ground soft and moist. Sunlight is also necessary, though not much. When the seedlings are grown at least 7 inches high, then you can take them out from the planting soil and transplant them in a row in a different place. Then go on watering and they will grow like anything.

This plant do not grow in cold countries, but if the plants can be kept inside house in warm atmosphere then it may grow. Should Tulasee be given to families who visit the temples? No, let them come and offer respects to Tulasee Devee instead. If they still want to have Tulasee Devee you can give them seeds and let the guests grow the plants from seed. Letter from Srila Prabhupada - May 5, 1971, Bombay

In North India, in Western UP, it is not practiced to grow Tulasee from seed, because it is believed that if Tulasee is grown from the seed, one has to marry her to Shaalgraam (Vishnu). Normally most people have a Tulasee plant in their house. If, somehow, ones Tulasee plant dies, he asks from his neighbor, because everybody has many plants in season as the seeds fall down from the plant in the nearby soil and grow themselves. So people take those new plants and people happily give it. In Skand Puraan Bhagavaan says to Brahmaa Jee - "Who give Tulasee to my Bhakt on asking and other people too, they go to my eternal Dhaam."
Besides it is not plucked on Sundays also.