Dust it. That's step one. Use something soft like microfiber. Do that regularly and you're halfway there. If you need to actually clean something beyond dust, then use a damp cloth, barely wet, then dry it right away. Don't leave water sitting, don't use harsh cleaners or ammonia stuff. Don't scrub hard. All that damages the finish. When spills happen, blot them up right away instead of wiping them around. Keep pieces out of the heat of any kind - sun, heaters, or vents. Sun fades things. Heat cracks wood.