To make a leather jacket costume look more Halloween-themed, focus on the details that give the outfit a clear character or spooky feel. Start with a black or dark-colored leather jacket and pair it with jeans, dark trousers, boots, or a simple graphic T-shirt. Then add accessories such as gloves, sunglasses, chains, patches, scarves, or a themed belt to make the outfit more distinctive.For a stronger Halloween look, choose accessories based on the character you want to create.