Buy a tupperware box and put silica packets inside. Wrap the DSLR with a soft dry cloth and keep it inside the box. While using it, keep the cloth back in the tupperware.
Always wipe the body with a slightly damp cloth when you use the cam in a dusty place or at a beach. Anywhere with dust or salty air.
Never ever change lens when the surroundings are damp or dusty.