In General ... we must obey the five pillars of Islam as it is said above ... and we mustn't eat pork, drink alcohol, smoke, take drugs (medical purposes is fine) ,no tattoo's. We only eat meat and food that is halal (being slaughtered and blessed the Islamic way. Similar to Kosher) We shouldn't date. We should dress and behave modestly.
Allah says :
( 33 ) Say, "My Lord has only forbidden immoralities - what is apparent of them and what is concealed - and sin, and oppression without right, and that you associate with Allah that for which He has not sent down authority, and that you say about Allah that which you do not know."Quran (7:33)
the rules that the Muslim must obey are the five pillars of Islam 1st pillar: saying there is no god but god and Muhammad is his profit 2nd pillar: praying five times a day 3rd pillar: giving to the poor and needy 4th pillar: fasting during the holy month of the Ramadan 5th pillar: traveling at least once to mecca on a hajj I believe those are the only MAJOR rules for a Muslim. Im sure there are more.