Know your hard limit that you have the money for and don't go beyond it, and be cool calm and collected.
Also as Kingpins said if no one else is bidding on the property don't bid against Vendor Bids as it really looks like a joke when someone is just bidding against the vendor - let the property get passed in and negotiate under non-auction conditions.
Don't worry if you miss out there will be other opportunities and if you get it you will probably be physically and emotionally drained from your first experience - but if you have kept to your limits then know you have done alright based on your own workings.
One other tip and it goes for any purchase it is worth signing the contract as " and or nominee" as it then gives you the freedom to put the property either in your name, some other structure or even someone else's name.
