It doesn't matter whom you vote for, as long as you vote.
This is possibly the biggest mis-statement of all.
If it didn't matter whom you voted for, voting would be a waste of time.
You may only be one voice among many, and in all likelihood not one result will hinge on one vote, but your vote still matters a great deal.
A final reminder about the referendum, because it doesn't seem to have sunk in everywhere (I must have answered the same question on half a dozen facebook threads in the last day or so):
Everyone has the option of voting in both part A and part B.
You don't have to if you don't want to, but you can. Even if you spoil one of the votes, the other one can still count.
And if you choose to vote in part B, please vote honestly, not tactically. There are a whole bunch of things that could happen over the next three years that may mean that whatever comes top could win in a referendum run-off: the world economy could tank, whoever is in government might do something that annoys everyone, or people might find they just really hate politicians, and decide to vote for change. Nothing is guaranteed, and any system could win, so you should do what you can to make it one you'd be okay with.
And finally, enjoy democracy. It's pretty cool.