1. Start by reading the directions
Even the best dishwasher won't perform at its peak if you don't load it properly. So read the dishwasher instructions to get the most of it. And be sure to save the manual whenever you buy a new dishwasher. If your dishwasher isn't new, look up the model on the internet and search for best tips there.
2. You don't have to pre-rinse
With most modern dishwashers it is not necessary to pre-rinse. Rather, it's best to scrape big chunks of leftover food before loading. Nevertheless, if you opt for this option, it may help a bit.
3. Know what the top and bottom racks are for
Use the top rack for concave items such as bowls, mugs, and glasses or large silverware and utensils. This is also where you should place dishwasher items made of plastics. The bottom rack is used for plates and platters and usually, cutlery.
4. Load the bottom rack so water can flow to the top.
Stack your plates and platters vertically and stagger large and small pieces so that they don't block the water or the detergent from getting through to the top rack. Oversized items such as boards should go along the perimeter of the bottom rack.
5. Load the top rack so water hits the inside of your bowls
Bowls should be angled so that they all face the center and should not be overcrowded. This increases the risk of breakages and impedes the flow of water and detergent. Glasses and mugs should be placed between the lines rather than on them. Dishwasher safe plastics also belong on the top rack away from the heating element.
6. Arrange your cutlery basket
Forks and spoons should have handles placed face down, but knives should be placed with their handles face up. Cutlery should be mixed so that they will be washed better as opposed to grouped. For best results, however, cutlery should be washed by hand.
7. After you load it properly...
Even if loaded well, it won't perform at its best if using cold water. To prevent this from happening, run your kitchen sink until the water gets hot. And keep your rinse-aid dispenser filled to make sure everything dries streak-free, too.
If the above information still wasn't enough, take a look at this video below, showing you exactly how best to load a dishwasher: