I guess this is sort of obvious, after living expenses, every sent goes into the house. We used to put all income into the loan and use the credit card, but we spent more than we should have. *blush* So we came up with the idea of a house keeping account. It really just an electronic envelope system. Pay goes in and automatically a set amount goes into a card account and that's housekeeping. It works very well for us. Sometimes we have money build up and then cam do some bulk buying and even fabric as the post below indicates ;o)
Have a play with home loan calculators and you'll be so shocked at what a difference a few extra dollars to each payment make. It's quite inspiring.
Something like this will get you going: http://www.commbank.com.au/personal/home-loans/tools-and-calculators/home-loan-calculators.aspx