Julie Barlow, co-author, Montreal and Quebec City for Dummies and The Story of French, offers the following tips to visitors:

• Language: People usually will speak enough English to understand you, but when approaching someone for the first time, it’s polite to excuse yourself for not speaking French and ask if it’s OK if you speak in English.
• Conversation: Conversational style among Montrealers tends to be quite direct. Discussions can be heated and demonstrative in ways that outsiders might interpret as impolite or confrontational, but they aren’t meant to offend—this is just an invitation to jump into the fray and mix it up.
• Street Life: Street life is very important here. In summertime, people eat on their balconies and in parks, and occupy public spaces with their private concerns.
• Personal Space: Personal space is not considered paramount; the city is compact and dense, and everybody is squished together—quarters can get shockingly close on public transit!
• Dining Out: Life in Montreal is all about eating—even if you can’t become fluent in French for your trip, it’s worth learning to find your way around a menu. And you’ll have more fun in Montreal if you eat later, when the restaurants are full and everybody is out (7:30 p.m. for drinks and dinner reservations at 9 p.m. are customary). Service in restaurants is brusque and professional—waiters keep their distance and aren’t too chatty or in-your-face, and they won’t come to ask every five minutes whether everything is to your liking.
• Kissing on the cheek: The custom of kissing on both cheeks, or faire la bise, is prevalent. The rule of thumb is, if someone reaches out to kiss you, you should let him or her, within reason—once on each cheek. It’s less common in professional situations, unless two people have become socially friendly.

source: http://travel.nationalgeographic.com/places/places-of-a-lifetime/montreal-cultural-tips.html