Orange represents autumn harvest and pumpkins, black represents night and mystery, and this is the most basic combination. For more depth, add purple (witches/magic), neon green (poison/glow), or off-white (ghosts/bones).

For symbols, pumpkins, bats, spider webs, ghosts, witch hats, and tombstones are the most common. When decorating, pick 1–2 main motifs and repeat them, which looks cleaner than piling on every element