Swap simple carbs for whole grain or wholemeal.
Put at least one vegetable into every meal e.g. spinach at breakfast, carrot at lunch.
Portion control is key. As a society, we eat way too much. The only way to combat this is to follow a portion control recipe (300- 500 calories for main meals).
Cultivate the habit of preparing and eating home cooked meals. Restaurant food is known for having excess salt, sugar, fat and other nasty hidden ingredients.
Eating any fruit and vegetable is great. But note that the dark coloured ones, are packed with powerful antioxidants. E.g. beetroot, berries, spinach etc.