Vacation rentals can be rented directly from the owner or through a vacation rental agency. With the wealth of information on the Internet, it's easy to track down either type of rental.

Which way should you go? It's up to you. "For a new person, I think it's better to work with an agency," Kenny says. Vacation rental companies, particularly ones with local offices, can often provide tips on things to do in the area—and if serious problems arise, a company may be able to move you to another of its properties.

Many websites that provide rent-by-owner listings have feedback sections and oversight of the properties listed. Reading property reviews can help narrow down your choices. "I am very hesitant to book anything I haven't read a review of," Kenny says.

As you search, it's important to know what you're looking for. How many people will be traveling in your group, and how will they use the house? If Uncle Bill's snores keep Aunt Edith up at night, maybe they'll want two bedrooms. "Concentrate on the space you're going to occupy and the people who will occupy it with you," says Scalzi of the Parker Company. He also recommends finding a place with a bathroom for every occupied bedroom.

Think, too, about what you'd like to do while you're on vacation. If you're planning to whip up five-course dinners with ingredients from the local farmers market, make sure the kitchen can accommodate your gourmet leanings. Need to hop online while you're away? Many rentals now have Internet access.

Don't hesitate to ask about amenities, exact layout, location, and anything else you might want to know about your potential rental when you contact a rental agency or an owner. "There's really no substitute for calling or emailing and asking the questions that are important to you," says HomeAway.com's Sharples. If the property's listing says "steps to the beach," ask the owner or rental agency exactly what that means. "The people who ask the most questions are the ones who don't end up with any surprises," he says.