If you're determined to get the lowest price on your next air fare, you'll need to set aside some time to check for deals.

Fare deals you find today still may be higher -- or lower -- than deals you find tomorrow. Fare rates change constantly. But if you watch fares over time you'll learn what typical high and low fares are -- and you'll be able to scoop up deals when a fare is lowest.

These are the sites worth knowing about for travelers intent on finding fare deals:

Cheap Airlines
They don't fly everywhere the Big Six carriers do, but if they're going your way, you can find good air fare deals. And you may be surprised by the little luxuries -- leather seats, personal satellite TVs -- some offer.

Price-Comparison Sites
Do you know how much you ought to pay for a plane ticket and also understand that fares fluctuate? Before you buy, get an idea of typical and current prices from these sites. On them you can compare air fares and search for the best deals.

Online Travel Agents
You never know when one of these will turn up a cheap fare deal. Expedia and Travelocity often have specially negotiated air fare deals with particular airlines, and you can save more when you buy a flight + hotel vacation package from them. These sites charge a small additional fee ($5-10 per ticket) when selling fares alone.

Go to the Source
There are no additional booking fees at official airline sites, and you may find an unadvertised Internet fare special or deals available during a certain time period.

Check for Bargains
Hotwire and Priceline have both been around for while. They sell "opaque" air fares, which means you won't know the specific major airline or time of departure until you pay for the ticket -- which makes some travelers, especially those on a rigid schedule, uneasy. Hotwire lets you search for a flight and returrns one low (but not always the lowest) fare. Priceline lets you bid on a fare. Once you know what the going rate is, start by bidding 25% under that fare and you may catch a deal. You will have to provide your credit card number in advance, and if Priceline accepts your offer, you've bought the ticket.

Air Fare Newsletters
SmarterLiving sends out a newsletter that reports the latest fare deals from any airport you designate. When you sign up for SmarterLiving's deals newsletter, choose the airport or airports closest to your home. Every week you'll have the latest fare deals delivered to you in an email. TravelZoo's deals newsletter lists the top 20 travel deals of the week, which range from air fares to cruises to vacation package deals.