A gallery wall lives or dies on planning. Before you buy a single frame, lay everything out on the floor and photograph it - that top-down view is the fastest way to spot a wall that feels crowded, off-balance, or one-note.
Rule one: mix two scales. A single large anchor print plus three or four smaller supporting prints reads more confident than a grid of same-size posters. The eye needs somewhere to land.
Rule two: keep 5 – 8 cm between frames. Tighter than that and the wall feels busy; wider and the prints stop reading as a single composition.
Rule three: hang the centre of the arrangement at eye level - around 145 cm from the floor. That's the museum standard, and it works in a hallway just as well as a gallery.