This quicktip saved me last night. I had to book a trip to London, without much flexibility in my travel dates so I locked in an intra-EU economy class ticket for an eye-watering €333.
22 hours after booking my ticket I checked a route on a different airline and it came to around €200. Without hesitation I called British Airways to cancel my original booking. If you cancel in the first 24 hours after booking, every penny of the booking is refunded, including credit card fees and even if it is a non-refundable booking class.
You can use this trick to see, at no-risk, whether cheap premium cabin fares can be bought for under the original price, via their Pro-Active Online Upgrade mechanism. It can certainly help where you need extra Tier Points and can often cost less than if you were to book the premium cabin outright.