There is a good article on strategic voting by Ben Raue in the Guardian – Election preferences: do you need to think strategically before voting in the lower house?. Generally voting is actually much more simple than some make it out to be – putting the candidates in the order of your actual preferences is generally the best way to go.
As all systems are necessarily flawed, there are always circumstances where a different strategy may actually produce a different outcome, but it is virtually impossible to get someone to win by strategic voting because it requires too much info on how everyone else will vote. In the article Raue rightly points out that this isn’t work doing – if you want someone to win then vote for them and put the other candidates in your order of preference. Voting to make sure someone loses can be a different matter as he also says, and I have addressed this in an earlier post as well: Strategic Voting: The Positives and Negatives