TheStreet has some good tips for saving on your airline tickets.
My simple ones are these:
Use comparison sites, especially Kayak.com. Kayak features Orbitz.com
but you may also want to use the Orbitz matrix feature which allows you to specify flexible dates. Having date flexibility can be a good key to lower fares.
Spend some time at it. Devote at least a few hours over the several months before your trip to find the best fares. Obviously this matters more for a family buying 3+ tickets than a single flyer so you can adjust that time committment accordingly.
Waiting until last minute is usually a bad idea, esp if only weeks are left, because you'll have to take whatever fare comes up. However you can also book too early. Summer discount specials often don't come up until spring and I've often found good rates into June for July and August travel though I don't like to wait that long.
Get on email alert lists for Orbitz and others. This will help remind you to keep looking and will alert you to fare decreases.
Don't forget your car - this can be more than the cost of the plane ticket, and car prices vary a lot. If you see one of those "129 per week" specials book it immediately. This year appears to be bad for car discounts. And...get a *small* car. Rates approach the absurd for SUVs and big rental cars. If you have money to burn get a small car, save hundreds per week, and make a donation to mosquito nets to save some lives.
Check out some of the new prediction tools for ticket prices like Yahoo's FareCast
