No one really knows where airfares are headed this year (beware anyone who claims they do; they're probably just trying to grab headlines). But here are 10 tips that will point you in the right direction next time you're looking for an airfare bargain.

1. Look for promo codes.

Airlines are increasingly resorting to promotion codes in order to bypass online travel agencies and meta search engines, driving traffic to their own sites, which are, after all, valuable properties selling everything from credit cards to hotel rooms. (Of course, this strategy also eliminates the need to pay commissions to other sites, but Airfarewatchdog suspects that this is only part of the story.) Discounts range from $10 to 50% off published fares. Southwest, American, Allegiant, Spirit, Air Canada, JetBlue, Virgin America and others used this strategy in 2008 and we expect to see more of this in 2009. To get the codes, sign up for the airlines' frequent flyer programs and emailed newsletters. These fares are never listed on Travelocity, Kayak, etc. (Airfarewatchdog lists promo codes in its blog postings as soon as they become available.)

2. Surprising sales sometimes appear on Saturdays and holiday weekends.

There is no one best day of the week or time of day to buy airfares. The best time is when the fare on the route and travel period you prefer (or are willing to travel), on an airline you like (or don't hate at least), goes down to its recent low point. That could be any minute of any day.

However, over 2009's MLK 3 day weekend, US Air launched an unadvertised sale to Europe for May, June, August, and September travel with fares up to 60% off the previous prices. This is not the first time we've seen a Saturday morning fare massacre and while it may not happen very often, for various competitive reasons, airlines sneak in the very best unadvertised sales when they think the competition is watching the big game or taking the kids to the movies rather than monitoring what other airlines are charging (Saturdays, and holiday weekends are an obvious choice).

3. Search for fares throughout the day, several times a day.

No one can precisely predict where airfares are heading (airfare pundits who claim to have a crystal ball should go play the oil futures market and make some real money instead of trying to get their mugs on the TV). Fares go up and go down throughout the day like the stock market, so if you don't like what you see at 10 AM, come back a couple of hours later and search again. Just as important as the fare, seat availability can change throughout the day. Airlines adjust the number of seats available at different fare levels, so even if the fare hasn't changed, the availability of seats at that fare may fluctuate, so you'll see a $120 fare to where you're going one minute, but the next it's twice that. Obviously, seats at the lowest fares sell quickly and in 2009 airlines will offer fewer seats at their lowest fares. If you see something good, grab it.

4. Use flexible date searches.

Adjusting your dates of travel by just a day or two can save hundreds, especially if you're buying for more than one person. This is one area where online travel agencies such as Orbitz, Cheapair, Cheaptickets, Hotwire, and Travelocity shine and often have an advantage over most airline sites and meta search engines. Travelocity will show you the lowest published fare (irrespective of seat availability) over a 330 day period on all domestic fares (except those on Southwest, Allegiant and a few niche carriers) and on major international routes; Orbitz and Cheaptickets do the same over a 30 day period of your choosing (on nearly all domestic and international routes, and they do a better job of assuring seat availability than Travelocity does). Look for the "flexible travel" box or "Find low fares for flexible trips" link on these sites and follow the instructions. In 2009, we predict that more airlines will offer some kind of flexible date search tool; last year, several added or improved this useful device.

5. Use Priceline, especially if you don't have a sufficient advance purchase window.

The cheapest fares often require a 7, 14, 21, or even a 28-day advance purchase. What if you need to leave tomorrow or on short notice? That's where Priceline's "Name your own price" bidding process can help. Typically, savings reach 40-60%, sometimes more. The site has added a page showing a daily list of discounts on the top 50 routes, revealing how much other users have saved by bidding on fares. Click on the route and you'll see actual bids vs. the lowest retail price

6. Sign up for fare alert services, but don't blindly rely on ones that monitor price only without considering seasonality.

Fare alert services (such as those offered by Farecompare, Yapta, Farecast, Travelocity, Kayak, Orbitz, Priceline and Airfarewatchdog [airfarewatchdog.com]) are valuable tools. Each offers its own advantages and limitations. But many of them alert consumers based on price only. So if the lowest possible fare between New York and London on a Friday is $600 RT but only for winter travel, and on Saturday the lowest fare remains at $600 but travel is valid for travel all summer at that fare, you will not necessarily receive an alert about this "higher value" fare in your email. Same goes for nonstop flights: many consumers prefer to fly non stop and justly believe that a $200 connecting fare is not the same as $ 200 nonstop, so choose an alert service that allows you to specify nonstops only or alerts you upfront that the flight is nonstop.

7. Search Southwest and Allegiant separately.

These low cost leaders do not share their lowest fares with third party web sites, such as online travel agencies or meta search engines. (They're also frequent issuers of promo codes, which are redeemable only on their sites.) Southwest doesn't always have the lowest price, but in many markets they're the only airline flying a route nonstop, even if just once a day. Plus, they have the lowest extra fees (see tip 10).

8. Use consolidators for international business and first class fares.

Especially with the economic downturn, business and first class cabins will be emptier in 2009, and deals will be amazing. Consolidators specializing in premium cabins will have some great deals, and the airlines themselves will be heavily discounting their premium cabins, so check the specials on their web sites. Do a google search for "first class consolidators" to see some of the firms in this space.

9. Check the airlines' sites directly.

We're not talking here merely about saving the $7 or $10 booking fee you might be charged on an Orbitz or Travelocity. Several international airlines regularly offer significant savings on various routes, but only if you buy from their sites. Among these are Aer Lingus, China Airlines, Singapore Airlines, Air Tahiti Nui, and Air Canada. Savings can be as high as $200 roundtrip.

10. Consider the extra fees before you buy.

If Southwest has a fare of $198 round-trip and United has one for $148, and you are checking three bags, then Southwest actually has the lowest fare because Southwest charges nothing for the first two checked bags, whereas United would charge you an additional $165 each way for three. You can find baggage fee charts here.

(Agencies via China Daily February 17, 2009)