Eavesdrop relentlessly, steal glances at outfits and actions, the way they stand and talk with their hands, how they react to someone invading their personal space, and, this is the crucial step, ask yourself why they do all of these things. Develop theories. Even if you’re wrong, you might be right. One exercise I like to do while I walk around town or stare at the people on the sidewalk below my apartment’s window is to look at someone and ask myself who I would have to be in order to love them.