How do you prevent being cheated when buying a house?

[Galit Garsiel]

I've heard about people who paid someone to build a home, and that person disappeared with their money and left the country. Heard about a stint where people paid money for a home in another country, and the company in charge sold them basements and storage instead, and took their money. 

Aside for buying a house that exists and not being build, and visiting the apartment for sale and seeing it for myself, what are precautions are there to take?