I find that temperature has more effect than anything I do. Since Spring arrived my mileage has gone from low 40mpg to mid 50mpg.
However I find the car does best when:
I keep in the right lane and go fairly slowly (not to be dangerous or discourteous).
Use CC as much as practical... except where steep hills are involved.
Try to anticipate and minimize use of brakes.
Drive with the load in hilly situations.