Just like any other bird, you want them to set for a couple of days before cooking. The leg should be easy to move, the joint loose.
Low moist cooking is best. So, you put them in a roasting pan with a little water and cook at 325 F. I like to put sliced carrots and potatoes and maybe celery on the bottom so the bird rests on vegetables instead of sticking to the pan. It also keeps the bird out of the water.
Cook with lid off and about 400 degrees for a few minutes to crisp the skin, then cover with lid and reduce to 325.