Sufism has been defined many different ways. It is the state of knowing the truth of one's innermost heart, that selfless place of freedom that enables one to live at peace. Sufism is the best of manners. The state of Sufism is common human potentiality, and in that sense it transcends religious, cultural, and linguistic boundaries.
Some have linked Sufism to Islam, saying the Sufis are the mystics of Islam. This is, in a way, true, however, Sufis see their tradition a pre-dating Islam, going all the way back to the first human spiritual experience, and contained within the original prophetic teachings of Judaism and Christianity, as well as Islam. Since Sufism refers to a state, it is not the same as practicing a religion. Shadhiliyya Sufis hold that one's outer life as as important as one's inner life, blurring the distinction between an "inner and "outer" practice.
Sufism is designed to bring you into close proximity with your divine aspect. One begins to identify with something much larger than oneself, and is thus able to be one's full self. Some Islamic scholars have defined Sufism as the science that allows one to achieve the second half of the Quranic message: that of how to be rather than what to do.
Sufism is an efficient means to achieve the witnessing of unity, or one's divine aspect. The path consists of teachings, practices, and community. One first needs true sincerity and humility. One must be ready to learn, rather than bringing a "full cup" of one's own knowledge to the table.
A "Guide," or spiritual master, helps every student to navigate the levels of reality as they "walk." The teachings, practices, and the Guide help the student through the 4 layers of their heart: the self, heart, soul, and secret, in order to indentify with their innermost divine aspect. The Guide is a humble helper, and the student always retains his/her own free will. Some students choose to be initiated into the Order. This involves a solemn promise to live one's life in a pure and holy way, and to try and improve oneself according to the Sufi teachings.
Practices are assigned. Some are individual, while some are done in commmunity. There is no "have to." You may practice what you choose at your own pace. Having spiritual community is an important part of our Way.
No, schools of Sufism can be quite different from one another. Not all are equipped to help one walk into the final stations of realization. Practices can differ as well. In our school, we don't "whirl," or "dance." Instead we have a remembrance practice that helps the energy to circulate and move the student form station to station.
It used to be that most Sufi schools were underground and hard to find. These days it is quite easy to contact many authentic schools. Many people encounter Sufism through the extraordinary presence of students or teachers, or through a spiritual teaching that inspires them to want to go deeper. We are often brought what we have asked for. In that sense, if you have encountered a Sufi group, they may be able to help you fulfill your spiritual goals. Our "tariqa" has chapters in most major cities. We would be happy to meet with you.
As a student of Sufism in our school, you need not necessarily change your outer life at all. You are not asked to be an ascetic or to quit your job or relationship. Most Sufis are very much about "being in the world," making a difference, but not "of the world." You will likely experience greater strength, peace, and love in yourself and in your relationships. You may come to understand yourself and your purpose in a deeper way. You can make friends that are walking a spiritual path as well.