Try to not sit on the backrest of the sofa as it may affect its structure and stability.
Do not keep warm or cold items directly on the furniture surfaces, instead, use a hot pad or coaster, do not keep hot items like a pan or baking dish even on a hot pad.
To protect your furniture from fading, avoid keeping your furniture next to windows and other places where it can be exposed to direct sunlight
The seating foam of the sofa may get softer after a period of time as the foam has a natural tendency to get softer after usage, but that doesn't mean it has manufacturing defects.