In Islam, there are five basic practices that all believers must abide by, called the “Five Pillars of Islam.” These are:
- acknowledging that there is no God but Allah, and Muhammad is his only messenger;
- the requirement of daily prayer, five times per day, with the supplicant facing the direction of the Ka’ab in Mecca;
- the requirement of giving to charity;
- fasting on the sacred day of Ramadan;
- and the requirement all Muslims have to take a pilgrimage one time in their life to Mecca, the holiest site of Islam.
These are the most basic acts of Islamic practice that all Muslims are required to observe in order to accurately practice the faith. However, they are supplemented by a large number of injunctions against certain kinds of immoral behaviors (such as the drinking of alcohol), which are explicitly set out in the Quran.
In response to the second part of your question, what primarily set the Muslims apart from other Arabic and Bedouin tribes during the period of the birth and expansion of Islam (610-750 C.E.) was their internal recognition of the cohesiveness of the Islamic community, the ummah. There is a very good book about the strength of the early Islamic ummah by Fred Donner called Muhammad and the Believers Movement. Donner’s central argument is that what gave the early Islamic community such strength, and what made it appear so attractive to outsiders, was the genuine conviction that Muslims portrayed in their beliefs.
While various other Arabic tribes of the Arabian Peninsula were engaged in petty handicrafts or were overly concerned with getting rich through trade and commerce, the early Islamic community conducted themselves first and foremost according to their strict adherence to the word of Muhammad and the physical and spiritual sacrifices they were willing to make in the name of their religious beliefs. This kind of rigorous commitment was unusual for a period in which most Arab traders were concerned primarily with acquiring wealth.