One hero object per room
Choose the object the player should remember: ritual device, damaged medical chair, locked cabinet, altar, abandoned terminal or another clear focal prop.
Build a reusable secondary-prop family
Doors, cabinets, shelving, lights, pipes, crates, signage and small clutter should share materials and scale so the scene reads as one place instead of a kitbash.
Use damage variants selectively
A clean/damaged pair for a few repeated props is more useful than unique destruction on every object. Variants create progression and storytelling without multiplying production cost uncontrollably.
Design for darkness without hiding the asset
Silhouette, emissive accents and roughness contrast should remain readable under low-key lighting. A prop that only works in a bright preview render is harder to sell and harder to use.
Keep the pack legally original
Ride the genre wave, not somebody else's characters, logos or trademarked props. Position packs as psychological horror, industrial horror, occult, abandoned medical or similar original themes.