First, be sure you aren't overcooking your vegetables. Overcooked vegetables are mushy and most all of the natural flavor has been cooked out (you'll notice when you drain a pan and the water is really orange from the carrots or green from any green vegetables). Cook the vegetables until they are just tender to the fork, but still have a bit of resistance. Colors should still be bright. Overcooked vegetables are dull in color and very soft. Add butter, salt and pepper to bring out natural flavors.