Coastal air carries salt, and salt accelerates corrosion. Cars that live near the ocean age differently from cars in the highlands.
Wash the underbody regularly, not just the paintwork. Most rust starts underneath, out of sight.
Keep the air conditioning in good order. Damp cabins encourage mould in the vents and can leave a persistent smell that is expensive to remove later.
Check door and boot seals once or twice a year. Perished rubber lets in moisture, and moisture in the carpet is the beginning of a much bigger repair.