My suggestion: use analogies (in time and space). To Québec folks: I will draw comparisons with another language. Please see no offence in that.
I am a French speaking French-native. I just come back from a wonderful 2-week trip in Québec (Montréal, Tadoussac, Québec, Trois-rivières, Mauricie). I have been to Montréal and Québec several times in the past. I more and more get used to the specificities of the French spoken there, hence the following advices. As a comment, I have a friend from Alsace (a region of France close to Germany) who lives in Québec since 10 years. He had no trace of Alsatian accent, being from an Alsatian family. Yet, he caught a Québec accent very fast. We discussed about that, and went to the conclusion that French-Canadian is quite contaminating (in a neutral sense). So immerge as much as you can.
The first time I went from Boston to QC in a bus. In the Canadian part of the trip, the bus driver was talking with a passenger, quite fast.
I had hard time understanding them. Till I saw a fast-food sign, representing a man with a pointy beard. The logo said PFK. The logo was familiar, but it took me ten minutes to see the light. "Poulets frits du Kentucky". Or KFC, in pure French. I wish France does the same with most anglicisms.
From that time on, when I do not understand Québec French, I do try:
- in time: to unfold the meaning by analogy. A "Char" is a means for transportation. It was used a few decades ago. Remember that Québec parted from France in the past. Some say it is a form of "ancien français". While French Canadian kept traces of regional speech, this is not fully true. In a peaceful modern context, should be "une voiture" (a car). I recently heard (second hand) a Canadian coming back from Venice, and talking about the "kayaks" (gondolas). And under England's rule, it has be influenced too.
- in space: to unfold the meaning by translation. The closest neighboring country might have a huge influence. My Québec friend uses a lot of "american" expressions in everyday language. Often translated.
For instance, when I say "merci", the reply "bienvenue" is not common in France. But switch to English, you get "you are welcome", which make more sense in the present context. Sometimes, this is even about pronunciation. Trying to unfold pronunciation traits that could be akin to English could be useful too.
Indeed, I did that in Alsace. Unfamiliar expressions in French, when they are mapped to German, sound more idiomatic.
So, immerge, and unfold.
[EDIT] I am adding two recent postcasts on the "Nouvelle France"
that may help understand the complicated story of people in Québec. Also adding the notion of "Speak white", a racist insult used by English-speaking Canadians against those who speak other languages in public (more details here). This is illustrated in the version by Michèle Lalonde, at La Nuit de la Poésie, 1970, turned into a reggae version by F. Poirier, Speak White Reggae.