Please see the Pundit's Guide exhaustive analysis of how the strategic voting sites failed to deliver on their promise: to provide progressive voters insight into the likeliest party alignment that would unseat a Conservative or prevent a Conservative from getting into office.
Essentially, the performance of these sites make it clear that they are unable to provide quality, local, timely data that can achieve their objective. They frequently make wrong, counterproductive calls. They are even dishonest about their performance post-election. Fortunately, enough Canadians ignore these sites that their damage in the last election was limited.
The best thing for a well-informed, well-intentioned progressive voter to do is pay attention to their local race and choose the best candidate. Do not allow strategic voting sites to usurp your vote and misdirect it.
Strategic voting sites to ignore:
strategicvoting.ca (inactive since 2008)