The recipe for wild geese is quite different than that for domestic. If it's a wild one see if you can locate a copy of Angus Cameron's & Judith Jones' "The L.L.Bean Game & Fish Cookbook" I like the wild roast goose with apricot and apple stuffing. If it's a wild one with a dressed weight of more than 5 or so pounds it's more of a candidate for braising than roasting.
For domestic geese, roast at 325 F for 15 - 20 min per pound on a rack in a pan with 3/8" water, 1 diced medium onion & 6 - 12 peppercorns.
When water has boiled down (after about 3 hours) baste / paint with melted butter to brown skin.
Gravy can be made by adding two or three tablespoons of flour and then some two cups of water to the pan drippings and cooking until the desired consistency is achieved..