When preparing to buy a home, it is good to revisit some of the lessons our parents and grandparents learned long ago.

HOW MUCH CAN I AFFORD?

Your housing budget depends on your situation and priorities. Two-income households with strong earnings potential can probably spend a little bit more than one-income households — as your income rises over the years, your housing costs are likely to become a smaller piece of your expenses. (Of course, that is not necessarily the case if you later buy a bigger house.) The same goes for individuals who have saved extra money or people who may earn less, like teachers, but who are unlikely to lose their jobs. Just be sure you stick with a plain-vanilla 30-year fixed mortgage because payments will remain steady.

One exercise I remember from school involves simple math and planning. Write down all of your expenses. Break them down into expenses that are fixed (utilities, groceries, auto expenses, insurance, etc.) and variable (everything else). Now, look at the variable costs…what am I willing to give up that could be reallocated toward housing?

Another exercise is to start by establishing savings goals, and then working backward. Set aside 10 to 15 percent of your salary, preferably in tax-deferred accounts, and then work with what’s left over for living expenses and housing costs.

DO THE MATH

Before you start hitting open houses, sketch out a rough budget based on the 28 percent rule of thumb, using a simple mortgage calculator. For instance, a family that earns $10,000 a month — or about $7,000 after taxes — should keep their total monthly housing costs, including mortgage, taxes and insurance, to about $2,800 a month. In one example, the family may be able to spend $440,000 on a home, or about 3.6 times their annual income, as long as they can come up with a 20 percent down payment (and closing costs). If they finance the remaining $352,000 with a 30-year mortgage with a fixed rate of 5.5 percent (of course lower rates are available, but let’s be conservative here), that would translate into a monthly payment of about $2,000, leaving $800 to pay real estate taxes and insurance. That leaves $4,200 of their monthly after-tax income to pay for everything else, giving them some breathing room.

DOWN PAYMENT

A higher down payment is usually required, but if you have a good credit score, you can get by today with historically lower down payments (FHA loans are also an option). If you do not, or cannot afford a higher down payment, it can cost you dearly in the form of a higher interest rate or fees. The ability to put down at least 20 percent is often emblematic of your financial discipline and ability to afford the monthly payment.

TAXES

Consider the tax savings associated with buying a home, but do not use it as an excuse to buy more than you can afford. Property taxes and mortgage interest are generally tax-deductible, but only if you itemize your deductions. Itemizing makes sense when your individual deductions exceed the standard deduction. For many taxpayers in the 28 percent tax bracket who itemize, a $350,000 mortgage may reduce their tax bill by as much as $5,357 in the first year of the mortgage. Since you pay more in interest in the loan’s early years, your tax savings will decline over time.

RESERVES

Ideally, homeowners should have six months of net pay in the bank. But if you halve that figure and save three months of your take-home pay that generally translates into eight months of payments. That does not account for food and other necessities, but it does provide some cushion. Two-income households can get away with just a few months of savings put aside, but single-breadwinner households should have at least six months. You also need to account for unforeseen costs.