Shamanism is a term used to describe the rituals of various cultures around the world. In Western culture, the term is often used to describe newer traditions that borrow from different cultures or create their own practices. Many people have found fulfillment, knowledge, or ability to help others through all kinds of shamanism, but remember that traditional and non-traditional shamans do not always agree.
In shamanism, there is a use of medicines which are usually traditional medicines. An entheogen, or entity-forming agent, can be a powerful associate in influencing our consciousness, but drugs are not always necessary. You can learn how to improve your skills as a shamanism practitioner before using drugs in your practice and learn how to use drugs with a trusted human being watch over and take care of you.
Many legal substances are used in the tradition of shamanism, such as tobacco. In the US, medicines such as ayahuasca and peyote are legal or are in legal gray areas when used by people who can prove that they are part of a traditional culture. As in the use of ayahuasca, for example, it is usually only an ayawaska shaman who can give the medicine in the ayahuasca ceremony to those who need to drink it.
There is no common way to meet entities, yet in several traditions, a shaman is required to do it. When you are in a trance, meditation, or sudden unexpected experience, you may be able to meet an entity. It can be a natural spirit, a spirit in life after death, or even an entity considered a god by some. There is not a single person that can describe what you meet, yet an experienced shaman can assist you to distinguish that entity and guide you how to make a covenant with them, serve them, or control them, depending on the traditions you follow.
You have to remember that some of these entities may be evil or difficult to handle. Often, rituals that include drugs, sacrifices, or other sources of power draw the attention of potentially more dangerous entities.