If you're considering buying a foreclosed home, there's one rule that you absolutely must follow.

Do not try and buy one at the government auctions held on the steps of a courthouse or city hall.

It's a risky business, even for the professional investors that frequent those sales.

Bidders are usually not allowed to enter the home before the auction.

Without the chance to inspect the property, you have no idea what kind of shape the property is in when you buy it.

Most foreclosures are in poor condition.

Owners who couldn't afford the payments usually have little or no money to make repairs or do even routine maintenance.

Some are so angry about being evicted that they deliberately strip and vandalize the home before they leave -- selling off appliances, ripping out plumbing and electrical fixtures, ruining walls and floors.

Once you get the keys and walk inside, you may find out that the home requires expensive, time-consuming repairs that must be made before moving in or reselling the home.

That's why no one bids enough to cover the mortgage on most homes sold at public foreclosure auctions, and the mortgage servicing company that holds the loan takes the keys.

The mortgage holder then hires a real estate agent specially trained to sell what are called real-estate owned, or REO, properties.

The agent will allow you to inspect the home, get bids for any repairs or renovations you want to make and submit an informed bid on the property.

If you're in the market, click here to see all of our 10 smart moves for buying a foreclosure.