My question is one of just learning something new:
What exactly entails sādhanā in Tibetan Buddhism? I specified Tibetan Buddhism because that's where my questions have been, but I don't know how it relates to the other schools.
Now, I get the impression that Tibetan sādhanā for a particular buddha or bodhisattva is very structured and most require empowerment, which I guess is the same as "dīksha" (initiation, sorry if sound condescending explaining terms you all probably already know ). I've read that incorporating prayers to Chenrezig, Green Tārā, Manjushri (aspect of goddess Saraswati!), Praises to the Twenty-One Tārās and Medicine Buddha simply asking for blessings do not require empowerment. Maybe my question actually requires a book to answer, several of which on the buddhas' and bodhisattvas' characteristics and aspects I am about to start reading.
Sādhanā in Hinduism (I often mention Hinduism only to compare and contrast and learn; I'm not here to sell it. ) is pretty much any consistent method of achieving a goal. It can be a daily pūja @ home, which don't necessarily follow any prescribed steps or structure; daily temple attendance @ a regular time; it can be simply a round or multiple rounds of mālā japa; it can be bhakti (devotion) to one's ishta-devata, doing everything in his or her service (that borders on Hindu tantra, by weaving devotion and mindfulness of the deity into daily life); and so on. My sādhanā, like that of many people, is pretty fluid, incorporating any or all of the above. All of those can be done for any deity without diksha [edit: a lot of people do take initiation from a guru; some mantras can be chanted without initation, others need initation].
So cutting through all that verbiage..."What exactly entails sādhanā in Tibetan Buddhism?"