Booking cheap flights for the holidays

(NBC) - More people are putting off holiday travel planning this year.

A new survey from AirfareWatchdog shows 35 percent of travelers have not yet booked their flights for the 2018 holiday season. That's a 52 percent increase from last year.

The biggest problem: procrastinators often end up paying more for their ticket.

Experts suggest using a search service, such as Google Flights, to compare fares from multiple airlines. It also lets you know the best time to book, and alerts you when prices do drop.

Some low-cost carriers, including Southwest, won't show up in third-party search results, but it might be worth checking those airlines directly. Southwest is now the only domestic carrier that doesn't charge for checked bags.

It's also free to make changes or cancellations, so you can book now with the flexibility to change later.

You can also save money by extending your stay, or flying on a specific holiday, like Christmas or New Year's Day.

The days before and after a holiday are generally the most expensive days to fly.