The preparation for crispy roast goose involves preheating the oven to 180°C, peeling and cubing apples and onions, and roasting the goose for one hour at 180-220°C followed by seven hours at 80°C. Other tips for achieving the perfect roast goose include adding carrots, onions, and water to the roasting pan, and using a recipe from Oma or Chefkoch.de. The roast should be placed in the oven at 200°C with the breast down, and a traditional accompaniment is red cabbage and dumplings.