Keep mortgages to reasonable levels: Too much debt can cripple your lifestyle and expose you to excessive risk. A huge mortgage leaving you subsisting rather than living makes no sense. When thing go wrong, people with excessive debt all too often lose their homes in mortgagee sales.
Don't wear rose-coloured glasses when looking at anything financial: Make a list of pros and cons before proceeding - buying a house, car, boat - anything - and then be pragmatic, hard-nosed and use common sense.
Scams: Still heaps out there, especially by email - sometimes purporting to be from your bank. Be very wary. Even lawyers have been done for hundreds of thousands. Don't get caught.
Higher the return higher the risk: There is no free ride.
Putting your finances in the "too hard basket": Inaction will cost you in the long run.
"I'm too busy": Another form of procrastination that carries the same costs.
Invest in boom, despair in gloom: Be contrarian, and don't let fear or greed make your decisions for you. Learn about behavioural finance.
Avoiding life and income protection insurances: Pay attention to insurance. Do you know what your biggest asset is? Clue - for most of us, it's not our house.
Trying too hard to avoid taxes and getting your children a student allowance: Don't outwit yourself with complex structures and trusts, you will spend a lot of money, and the IRD and Winz are not stupid.