I have to admit that I have been totally ignorant as to how to use my credit card.
I found out some useful info yesterday and figured that it would be useful to share so that people don't make the mistake that I have been making.
My credit card has a 55 day interest free period for purchases.
I thought that the interest free period started from the purchase / transaction date. IT DOESN'T!
Your 55 day interest free period starts from the date after your statement date. This means that if you purchase an item at the wrong time you will not get all your interest free days and if you purchase during the statement periods your interest free days will be reducing.
At 20% interest that adds up to a lot of money.
I was also told by a customer service rep at Commonwealth that a credit card purchase of an item above $1000 allows you the option to give them a call and ask for a "Great Rate". The Great Rate is .99% interest for 3 months! That's a massive saving just for a phone call. They allow you one Great Rate at a time.
If you have more than 1 credit card you can also transfer the balance between the cards and get a rate below 5% for 6 months.
Hope that this is helpful.