Clipping for Krsna

Clipping and Storing her leaves and Manjaris
Clip the stalk below the first set of leaves at the base of the manjari or manjari unit (these may be small leaves) but as close as possible to the second set of leaves. When clipping, do not leave a small twig on her, as she will have to use energy to discard this now useless tissue. It is best to store the manjaris in large airtight containers so that they can 'breathe' and not dry out. They should keep for several days.
Here in India, manjaris are broken off with the fingers of the right hand. Fingernails are not used. However, some may have difficulty removing the manjaris cleanly, therefore a very small , sharp pair of scissors, used only for Tulasi, is recommended. When making a Tulasi garland, never use a needle to pierce her. Instead, knot or wrap the thread around the manjaris.
Store the leaves in a bowl of fresh water or in plastic, airtight containers and place them in the refrigerator. When using an airtight container, wash the leaves and pat them dry before placing them inside, as too much moisture will cause them to rot rapidly.
. .. whether we may prune the leaves of Tulasi. No, there is no question of pruning. But you can take leaves for worshiping Krsna from the Tulasi. First, utilize the dead leaves or leaves which have fallen down, and if more leaves are required for worshiping Krsna, you may take them from Tulasi plant in this way: First approach Tulasi Devi and offer your obeisances, requesting her that for worshiping Krsna you want to take some leaves. Then if she allows, you may take. There is no question of pruning in the manner of gardeners just to make a nice beautiful plant for ornamental purposes. And if there are any dead branches, these may be made into beads, like neck beads, and if they are large branches you can make japa beads. There is no need to keep a candle burning all night, but you can burn a candle in the evening for one hour for Tulasl Devi, that will be nice. (S rila Prabhupada's letter to Jagamohini Dasi)
When picking Tulasi leaves, chant the following mantra:
tulasy amrta-janmasi
sada tvam kesava-priya
kesavartharn cinomi warn
varada bhava sobhane
tvad anga sambhavaih patraih pujayami yatha harim tatha kuru pavitrangi kalau mala vinasini
"O Tulasi, you were born from nectar. You are always very dear to Lord Kesava. Now, in order to worship Lord Kesava, I am collecting your leaves and manjaris. Please bestow your benediction on me."
O Tulasi, being pure in body and the destroyer of the sins of Kaliyuga, I will worship the Lord using leaves coming from your body. You should make that worship successful.
Pick only the leaves that grow next to the manjaris (flowers) and the leaves that are ready to drop (they will turn a pale color) not the new, green ones. Pick the manjaris 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 Krsna'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 Tulasi Devi. This is a great offense. Remove dead branches if absolutely necessary. If branches obstruct a passageway, tie them back, but don't cut them.
One should pluck the leaves with the right hand, holding the branch in the left hand, being careful not to break the branches.
patranam cayane vipra bhagna sakha yada bhavet tada hrdi vyatha visnor diyate Tulasi pateh karatala trayam dattva cinuyat Tulasi dalam yatha na kampate sakha tulasya divyasattama
If when picking Tulasi leaves one breaks the branches, Visnu feels pain in His heart. One should clap the hands three times before picking Tulasi and pick in such a way that the branches do not shake. (Visnu-smrti)