It`s a really wide question because there are lots of different traditions in Amazonian region especially if we consider different part of Amazonia as Peruvian, Brazilian and other parts.
We work with Shamans from Loreto region of Peru. Its the center of Amazonian, Peruvian shamanism. First of all the tradition means that the person who leeds the ceremony is Curandero and Shaman and gained all the experience by passing the long way of dieting with sacred master-plants in Peruvian jungles for many years. Only by this process the person can become a healer and have the right and honour of guiding ceremonies.
Secondly the tradition means that you will have to follow some rules during ceremonies that are set for your safety, deep personal connection with the spirit of medicine and healing process during ceremonies. These rules include keeping silent except expressing emotions, deep respect to other participants, keeping your place during the whole ceremony except toilet, prohibition for singing and dancing, prohibition of interacting the experience of other participants. All ceremonies are passing only during the night time with no using lights or self-phones.
And finally the tradition means that a shaman never sing ballads or popular songs that have no connection to the healing ceremonies and in fact are disrespect to the spirit of the medicine itself. During ceremony process shaman uses special songs names "Icaro" that he learned directly from spirits during his/her dieting process with master-plants. Icaros and Chacapa (the traditional instrument made from leafs) are tools of a shaman for healing and protection people during a ceremony process.
All these rules are the result of thousands years experience and dedicated on your safety, personal healing and transformation.