Buy only what you can afford.
It's not hard these days to figure out what you can afford. The Internet is virtually choked with mortgage calculators to help you figure that out. You simply enter what you make and what you owe, and the calculator will tell you how much more the banks will lend you.
The lending environment has changed substantially over the past decade. Since crazed lending practices of recent years have ended, the banks have started imposing stringent requirements on applicants. You need a 20 percent down payment, and you need for your monthly outlay for houses and cars to go no higher than 36 percent of your income.
Even if you view the vacation home as a potential way to earn income, don't count on that income to help you pay for the house. Keep in mind that you don't have to buy the ultimate beach house with high ceilings and private docks. It's OK to start small.