When In Morocco, if you cannot do like the Moroccans, know at least what's appropriate behaviour. You may have heard the word proxemics. If not then simply put, it's how people interact within a specific space. In other words, it's spatial communication. While most foreigners, especially Americans, allow for a minimum 1 yard when conversing, Moroccans usually invade other interlocutors' vital space. Sometime they rub shoulders, use their hands and body to emphasise or hammer a point home. Under other skies such behaviour may be interpreted as rude, or tasetless and lacking etiquette. In Morocco, it's indicative of their attempt at friendliness--a gesture of warmth and acceptance. 

Also, it is a very good idea to speak a little French. French is their second language, so if you hear a local saying "Ça Va?", just respond saying "Ça Va". (It's about the equivalent of saying "everything is alright" in English, and it is pronounced "Sa Va")

If they do speak English, then you will hear the phrase "Hello my Friend" more often than you will hear the beeping horn of a passing Orange taxi.