NEW YORK ( MainStreet) — Prices for airline tickets and hotels are constantly fluctuating, making it tricky to pinpoint when to book your next trip.

Travel websites have completely changed the process of booking hotels and flights, while making it easier to save money, too.

There's no rule of thumb as to whether booking directly with the airline or the hotel will result in a better deal than using a third-party travel booking website, but it's worth booking your trip ahead of time to save money.

"For hotels, you'll be rewarded by booking as far in advance as possible, since hotels want peace of mind that rooms will be booked," says Pauline Frommer, Publisher of Frommers.com.

As with any purchase, prices are constantly fluctuating. If you book a hotel room in advance and the price drops, you're not out of luck if you use websites like Tingo.com, which promises to refund the difference.

When shopping online for clothing or electronics, consumers these days tend automatically to search online to see if a coupon code is available. The same mindset should apply to travel websites. "People don't normally associate travel sites with coupon codes, but it's worth checking to see if you can find one," says Jeanette Pavini, a savings expert with Coupons.com.

Chances are you've used sites like Priceline and Hotwire, which ask users to submit bids on hotel rooms, flights and car rentals. However, you may not have come across the website BiddingForTravel.com, where users spill the beans and reveal their previous bids to help others.

"The site helps travelers with their nervousness about bidding and also helps them come up with a savvier bid," Frommer adds.

As for airline tickets, Frommer suggests booking six weeks in advance to score the best deal. "If you book too early, the airline knows you have to travel, so there's no need to offer discounts. The same applies for booking too late, which is when business travelers tend to book," Frommer tells MainStreet.

Aside from how far in advance you book airlines tickets, it also makes a difference what day of the week you buy the tickets.

Airlines tend to set their prices on Mondays, but the best prices fall on Tuesdays and Wednesdays. "This gives the airlines a few days to compete over prices," Frommer says. "By mid-week, prices tend to settle." Weekends are also a popular time of the week to book tickets – and the airlines know this, hence the higher prices on weekends.

The booking of airline tickets is also taking a page out of the complex options market for stocks with the website OptionsAway.com. Using similar financial algorithms seen in the financial options market, the site lets you hold the flight you want to take for days or even weeks, for a small fee.