Tickling Dragons with get you Dragon Tears while brushing them will get you Dragon Scales. Make sure they have a Dragon Toy (obtained from Viki Vampress) and that they have enough garbage to eat. One way to get trash is to have your Sims eat snacks and not throw them away. Then, enable the move_objects on code an put the trash in the Dragon's room. Make sure you do not let the Dragon out of its room. Try to make two rooms and put a Sim in one with everything they need. They will live in solitude with the Dragon until you have all the desired Dragon items. Make sure that the Dragon and Sim are trapped or the Dragon will burn everything.