Everything about photographing here follows from the orientation. The hills of Alfama and Graça look north and east across the roofs, so they hold usable light from sunrise until about nine and then go flat; the riverfront from Cais do Sodré to Belém looks the other way and only becomes worth the walk after six. Getting that backwards is the single most common way a session here is wasted, and it costs nothing to get right.
The second thing is the calçada. The pavement is polished limestone, it is genuinely slippery, and it is on a gradient almost everywhere worth standing — which is a wardrobe decision rather than a poetic detail. The third is that the city centre is small: Graça to Portas do Sol to Alfama is twenty minutes on foot, so a ninety-minute session takes in three distinct backdrops without anyone getting into a car.