One big thing people should do, and I know a lot of people here don't like it, but couples should really discuss whether living in the applicant's country is a possibility.
It should be a huge red flag for anyone if your spouse seems too deadset in coming to Canada, and refuses to live in their country for any reason, unless they were a successful refugee claimant. This possibility should be brought up from time to time in conversation. People dupe their sponsors because they want to live in Canada, to separate them from genuine people, you need to read their feelings and ask them questions if living in Canada is not a possibility. If your spouse is capable, and willing to live in either Canada or their home country, both of you will be less stressed because no matter the outcome of the PR application, you both will still end up together, rather than divorce should the PR fail because you both cannot live together since your spouse refuses to live in their country.