Rules of Chopstick Etiquette

Never stick your chopsticks upright in your rice bowl. (This is used to honor the dead at a family altar or gravesite). Place them on the chopstick holder-- usually a small ceramic or metal oblong by your plate when you are not using them.

Don’t lick your chopsticks if you are in public.

Try not to let the tips of your chopsticks touch your lips or tongue if you are using them to remove food from a communal plate, as this is unsanitary behavior.
Don’t stab your food as though it were a giant toothpick.
Don’t dig around in the food if you are eating “family style” from common bowls or platters of food. If your chopsticks touch something, it’s yours.

Source: “Everything You Need to Know to Understand China A to Z”, by May-lee Chai and Winberg Chai