One of the best ways to keep ham moist is to cover it with foil while baking. This will help trap the natural moisture in the meat and prevent it from drying out during cooking. Additionally, basting the ham with a glaze or mix of oil, honey, and broth can also help keep it nice and moist.  Be sure to cover the ham in between basting sessions and remove from the oven when it has reached an internal temperature of 145°F.