I recently read an article in USA Today with tips on how to avoid additional costs when booking flights. One tip which I've not heard before was don't book airline tickets at night. Apparently airlines release a small number of discounted coach tickets in the mornings or early afternoons. When you book later in the day you have less of a chance of grabbing a deal. I decided to put this theory to the test as I was looking for a deal on a round trip flight to Vegas. On Wednesday morning this week I found an awesome round trip deal departing from Richmond, VA (RIC) to Las Vegas (LAS) for $251. I wasn't able to book it that moment because I needed to confirm my time off at work. Later in the day I went back and the price for the exact same flights rose from $251 to $335. I decided to wait till Thurs morning to see if the same round trip deal for $251 would come back. Throughout Thursday morning and afternoon I kept checking and the price remained at $335. Since I'm not traveling till February I decided to hold off and see if the deal would come back again in the next few days. This morning (Friday) I checked again and the $251 Round trip deal was back! So I'm now all booked and looking forward to my next trip to Vegas!
Here is a link to the USA Today article I referenced. There are other tips there that Insiders my find helpful in booking flights.