You've likely heard many of the IAM's suggestions, such as removing excess weight from the car's trunk and keeping the tires properly inflated, but they are good reminders in any case. Other common sense tidbits include accelerating at a less frenetic pace and obeying the posted speed limits.
Other less common measures can include removing roof racks, reversing into parking spots and driving with less than a full tank of fuel. Of course, it's not always practical to make these kinds of adjustments, but it's always a good idea to keep them in mind.
[Source: Channel 4]