If you want glistening, flavorful gravy that tastes just like Mom makes (or even better), try the classic recipe (shown, top). If your time and energy are waning, opt for the quick rendition (shown, bottom). No lumps either way.
If your gravy is too thin: Whisk 2 teaspoons cornstarch into 2 teaspoons cold water, or combine 1 tablespoon room-temperature butter with 1 tablespoon flour to form a paste. Whisk into 4 to 5 cups of barely simmering gravy and cook, stirring constantly, until the gravy thickens.
If your gravy is too thick: Add more of the reserved pan juices or warmed turkey or chicken broth, 1 tablespoon at a time. Or try a splash of a flavorful fortified wine, such as Madeira or sherry.
If your gravy is too pale: Try a few shakes of soy sauce, keeping in mind that paleness is only a cosmetic concern, unrelated to flavor.