1) Watch the calendar.
Magic Kingdom is notoriously more crowded on weekends, Mondays and holidays. EPCOT has higher attendance on Tuesdays and Thursdays. You’re pretty much good to go at Hollywood Studios and Animal Kingdom on most days. But when you’re making your trip itinerary, it’s good to pass on Magic Kingdom until Tuesday, Wednesday or Thursday of your trip if you can, and if the crowds bother you, be sure you plan to visit EPCOT on a Monday, Wednesday or Friday.