“ If you want to add a 'supernatural' touch to your campaign, define the rules of magic and the universe. Make your players comfortable with those rules. Then your new supernatural creatures must then break those rules.”
“ A young girl with a dirty face and tattered dress stands near the town market offering to sell the PCs freshly cut flowers. They are only a single copper a piece, and smell nice. Perhaps the PCs will be generous with their wealth, or they will not. Great for paranoid parties.”