Put plastic in the top rack, farther away from the heat source.
Load items at an angle with dirty surfaces facing down, so they are sprayed directly. Make sure bowls and plates don't overlap.
Check that nothing will block the detergent dispenser or upper and lower spray arms.
Load sharp silverware pointing down. Use the slots in the silverware basket covers to keep items separated. Flip up or remove the covers if your silverware won't fit.
Unload the bottom rack first and leave plastic items for last, so any leftover water won't drip on your dry bottom rack dishes.