Personally, the thing that has consistently worked is portion control. It will always be easier to eat only the calories you need, than to burn calories from over-eating.
People look at the "recommended serving" and cry foul that it suggests they eat only 30-40g of cereal in the morning, but it really is plenty. I keep a digital scale in the kitchen and weigh out most of my food before eating or cooking with it. Even things like rice and pasta are really easy to over-do when guesstimating and not measuring.
It can take a little bit of adjustment to get used to this, but your body quickly adapts to the portions you're being served. And then on days when you do more than your usual exercise, it's easier to add a snack or increase the portion slightly, than it is to be always trying to "reduce" the calories on days when you don't work out. It's a small mental trick that can work wonders once you've set a baseline.