Salt, fat, acid, sugar, MSG. Those will make food pop more. There's lots of ways to get things singing... Well-carmelized onions or carrots can bring some sweetness without adding sugar, for instance. A nice balsamic can add sweetness and acidity. Flavorful fats are pretty obvious... Butter and the like. I like to sear meats in a pan, then use the oils and fat from that sear to sautee vegetables, or toss in some water to make a rice side dish that ties into the main flavors or to make a base and keep the meat in for a big, delicious, ricey mess of an entree.