What to wear for Sherlock: Black hat, heavy black coat, off-white dress shirt, and an ascot. Bring some props like a magnifying glass.
What to wear for Watson: Brown hat, brown coat, grey waistcoat with a pocket watch. White dress shirt and a dark tie underneath. A moustache is a must.
How to act: You're supersleuths, so pretend you're at one of those murder mystery parties or in a game of Clue.