Unfortunately this is a real picture of my wife not listening to my instructions. 

NEVER: Put your knives into the dishwasher. The dishwasher will cause your knives to bang into each other resulting in dings and damage to your blades. The blades can also become warped due to the heat in the drying process. The dish detergent damages the integrity of the steel.
ALWAYS: Hand wash your knives with warm soapy water and dry them immediately.

NEVER: Put your wet knives in the knife block without drying them first. The wet knives can develop rust and the water may also cause mold or mildew.  
ALWAYS:  Dry your knives right after washing.

NEVER:  Use your knives on glass, stone, granite or marble when cutting. Cutting on these materials will cause damage to the knife blade and also cause the knife to dull much quicker than normal.
ALWAYS:  Use your knives on wood, plastic or bamboo cutting boards.

NEVER: Put your knives in a drawer with other knives or utensils. Storing them this way can cause them to bump against the other  items causing nicks and ding damage to the blade.
ALWAYS:  Store your knives in a knife block or place each blade in a plastic sheath.

NEVER: Use one knife for every job. My wife seems to think that a steak knife is the only knife that needs to be used from chopping to slicing and dicing.  
ALWAYS: Use the right knife for the job.

NEVER: Use dull knives. You have a greater chance of injury trying to use a dull knife, rather than a sharp one. When using a dull knife you have to use more pressure causing a greater chance of the knife slipping and causing injury.
ALWAYS: Use sharp knives.