In the 2011 federal election, 400,000 Greens voted strategically to stop Harper. But it had no effect. He still won a fake majority on 39.6% of the vote.
Why? Green voters are left-leaning and all of Harper's 40% came from the right side: blue Liberals, red Tories and hard-core cons.
The same is true in the present Ontario election. Left-side voters can't stop Hudak because he needs right-side votes to win.
How neo-cons are stopped
In order to stop the neo-con party from winning, the Liberal and NDP parties have to appeal to right-leaning voters.
The Liberal party typically tries to win over red Tories with moderate neo-liberal ideology.
The NDP appeals to voters with pocket-book issues that offer real savings for individuals and families — as opposed to neo-con tax cuts that primarily benefit the rich. (Although Liberals sneer at this as “populism,” it's actually left-wing populism, not right.)
Exception to the rule
In swing ridings where there is a clear two-way race between the PC candidate and another candidate, strategic voting makes sense.
Just keep in mind polls are far from accurate. In a three-way race your strategic vote could help rather than hinder vote splitting.
If you are a left-leaning voter, voting out of fear won’t do any good. Best to stick to your principles — and fight for voting reform to put an end to the nonsense.