Interest on mortgage, and property taxes. (Only if you itemize on Schedule A instead of taking the Standard Deduction.)

If it's rental property, you can also deduct insurance and maintenance, whether or not you itemize. If it's a duplex and you live in half and rent the other half, you can deduct half of these costs.

When you sell your home, you don't have to pay any taxes on the gain, in most cases.

Your house is your investment. When you buy your house, your stake in the house is equal to your down payment. (If you put 10% down, you own 10% of the house when you start.) As you make monthly mortgage payments for 15-30 years, you'll gradually own more and more of the house. Also, the house will get more valuable over time. (Figure at least 3%/year.)

Once you've paid your house off in 15-30 years, you no longer have to make a monthly mortgage payment. All you'll have to pay is taxes, insurance and maintenance. Besides that, you live for free.

A possible mistake is paying more than the house is worth.