For most people, buying a house involves a double financial whammy.

First you have to assemble a pile of cash for the down payment and closing costs. Then you must convince a bank to lend you an even more staggering sum - generally 80 percent or more of the purchase price.

So your first step, even before you start the actual hunt for a property, should be to get your financial house in order.

Start with your credit

Credit reports are kept by the three major credit agencies, Experian, Equifax, and TransUnion. Among other things, they show whether you are habitually late with payments and whether you have run into serious credit problems in the past.

A credit score is a number calculated by Fair Isaac based on the information in your credit report. You have three different credit scores, one for each of your credit reports.

A low credit score may hurt your chances for getting the best interest rate, or getting financing at all. So get a copy of your reports and know your credit scores. Try Fair Isaac's MyFICO.com, which charges upwards of $50 for all three reports and scores.

Errors are not uncommon. If you find any, you must contact the agencies directly to correct them, which can take two or three months to resolve. If the report is accurate but shows past problems, be prepared to explain them to a loan officer.

Know what you can afford

Next, you need to determine how much house you can afford. You can start with one of the Web's many calculators. For a more accurate figure, ask to be pre-approved by a lender, who will look at your income, debt and credit to determine the kind of loan that's in your league.

The rule of thumb here is to aim for a home that costs about two-and-a-half times your gross annual salary. If you have significant credit card debt or other financial obligations like alimony or even an expensive hobby, then you may need to set your sights lower.

Another rule of thumb: All your monthly home payments should not exceed 28 percent of your gross monthly income.

The size of your down payment will also determine how much you can afford.

Line up cash

If you haven't already, you'll need to come up with cash for your down payment and closing costs. Lenders like to see 20 percent of the home's price as a down payment. If you can put down more than that, the lender may be willing to approve a larger loan. If you have less, you'll need to find loans that can accommodate you.

Various private and public agencies - including Fannie Mae, Freddie Mac, the Federal Housing Administration, and the Department of Veteran Affairs - provide low down payment mortgages through banks and mortgage companies. If you qualify, it's possible to pay as little as 3 percent up front. For more, check out their Web sites at Fanniemae.com or Freddiemac.com.

A warning: With a down payment under 20 percent, you will probably wind up having to pay for private mortgage insurance, a safety net protecting the bank in case you fail to make payments. PMI adds about 0.5 percent of the total loan amount to your mortgage payments for the year. So if you finance $200,000, your PMI will cost $1,000 annually.

Increasingly, though, lenders are giving qualified buyers the option of using "piggyback loans" to cover a portion of a home's down payment and avoid paying PMI. These second loans are usually in the form of a home equity loan or line of credit for 10 percent to 15 percent of the home's purchase price.

Once you've considered the down payment, make sure you've got enough to cover fees and closing costs. These may include the appraisal fee, loan fees, attorney's fees, inspection fees, and the cost of a title search. They can easily add up to more than $10,000 - and often run to 5 percent of the mortgage amount.

If your available cash doesn't cover your needs, you have several options. First-time homebuyers can withdraw up to $10,000 without penalty from an Individual Retirement Account, if you have one, though you must pay taxes on the amount. You can also receive a cash gift of up to $12,000 a year (the limit for 2006) from each of your parents without triggering a gift tax.

Gift taxes are paid by the donor, not the recipient. (In fact, if you and your spouse's parents are both well-heeled, they can give you a total of $96,000 in one year - $12,000 from each of the four parents to each of you.)

Check on whether your employer can help; some big companies will chip in on the down payment or help you get a low-interest loan from selected lenders. You can also tap a 401(k) or similar retirement plan for a loan from yourself.