In addition to being a common topic of household arguments, it's one of the most frequently asked questions at the popular Clean My Space housecleaning sites: What is the best way to load a dishwasher?
Before loading, ensure that you have detergent that is safe and effective for your model of dishwasher. It's also a good idea not to stock up more than two months' worth at a time -- according to Good Housekeeping, detergent will deteriorate over time.
To pre-rinse or not to pre-rinse... that is the question that probably sparks the most arguments between primary dishwashers in a home. The answer depends entirely upon your mess and your schedule: dishes that are oily or will be sitting in the washer for a while should probably be pre-rinsed. Additionally, if your dishwasher is less effective than you'd like, you should probably help it out with a pre-rinse.
Load the bottom rack with plates and bowls and dishwasher-safe pots and pans, working with the tines to maximize space. Put flatware in its basket, ensuring that sharp knives point downward; if there are no separators, load carefully to prevent flatware (especially spoons) from nesting.
Large items -- platters, cutting boards, etc. -- should be loaded in the back or on the sides of the bottom rack, with the dirty side facing inward. Do not load plastic items on the bottom at all. Finally, close the bottom rack and ensure that the spray arm (located under the top rack) can spin freely.
The top rack should hold items that are made of plastic or are small, like condiment bowls, in addition to mugs, glasses, and stemware. Place items between tines and without touching each other, to allow for maximum cleaning and reduced clattering during the cycle. Items should be upside down and angled if possible, to reduce pooling in the bottoms.
Utensils can lay flat on the top rack, staggered and facing downward; ensure that they do not slip through any holes and interfere with the spray arm.
Ensure that dishes are not stacked or overcrowded -- if surfaces can't be reached by water from the spray arm, they can't be cleaned.
Finally, a note about what NOT to put in your dishwasher. The Kitchn recommends avoiding loading: insulated mugs, delicate china or vintage dishes, high-quality knives or items made of wood, crystal, silver, gold, copper, or cast iron.
Always check your dishwasher's manufacturer instructions for detailed information.