Most Asian countries use chopsticks instead of cutlery. Asian cuisine restaurants in Westerner countries will provide you with cutlery if you ask, but it is more elegant and sophisticated to use chopsticks with the proper etiquette.
What chopsticks etiquette is
Chopsticks etiquette is the set of rules to properly set, use, and rest chopsticks. Such rules help avoid behaviors that can disrespect and irritate hosts or guests.
Chopstick etiquette in principle is similar to cutlery etiquette to set, eat with, and rest utensils. However, there are some significant differences between chopsticks and cutlery etiquette.
There are several methods to handle chopsticks due to cultural differences. Nevertheless, some general principles are valid across countries.

Chopsticks etiquette rules

1) Hold chopsticks so they do not cross
You should hold and move your chopsticks so they do not cross.
Place the first chopstick in the junction of your thumb with the hand. Rest the end of the chopstick on your third and fourth fingers. Place the second chopstick between your thumb and the second finger, and hold it down with the tip of your thumb.
Alternatively, place the first chopstick in the junction of your thumb with the hand. Rest the end of the chopstick on your fourth and fifth fingers. Place the second chopstick between your thumb and the second and third fingers, and hold it down with the tip of your thumb.
To grab food, move only the second chopstick on the top, and leave the first one firm on the bottom.
2) Use chopsticks solely to bring food to the mouth
Always use both chopsticks together, even to stir food or sauce. Using only one chopstick is against etiquette.
Use your chopsticks solely to bring food to your mouth or to touch your food. Do not bite them or keep them in your mouth too long.
In most Asian countries, you can hold the rice bowl up to your mouth and use chopsticks to push rice directly into the mouth.
However, in some countries such as Korea, etiquette requires always keeping your dish on the table. Thus, you cannot pick it up and bring it close to your mouth.
Do not point or gesticulate with your chopsticks. Do not use them to move plates or bowls on the table.

3) Do not stick chopsticks into your food
Avoid sticking the chopsticks into your food. In many Asian countries, it is considered bad manners and bad luck as it is similar to how incense sticks are used in funeral rites.
4) Do not rub chopsticks together
Avoid rubbing your chopsticks together. Rubbing chopsticks together is considered an insult in Japan, as it implies that you are trying to get rid of splinters because the chopsticks are low-quality.
5) Serving chopsticks are solely to take food from shared dishes
Serving chopsticks are usually of a different color from your individual ones. Use serving chopsticks to take food from serving dishes. After you have served yourself, return the serving chopsticks back to the shared dishes.
Do not use your chopsticks to take food from a communal plate, especially if you have already eaten with them. If you need a pair of serving chopsticks, simply ask for them.
Using your chopsticks to pass food to another pair of chopsticks is against etiquette.

6) Rest your chopsticks on the bowl or on the chopsticks rest
Do not rest the chopsticks on the table.
If you are taking a break or you have finished eating, place the pointed ends of the chopsticks on a chopstick rest. If a chopstick rest is not available, place the chopsticks flat, sideways across the rice bowl.
Do not place them vertically in the bowl, as this is traditionally done at funerals. Do not leave them crossed.
Asian countries have different etiquette rules on how to rest the chopsticks. In China, do not rest chopsticks pointing toward other guests seated at the table. In Japan, rest chopsticks horizontally with their tips pointing to the left.

Chopsticks etiquette: the worst mistakes
The Rude Index identifies and ranks negative behaviors.
A high score (8-10) means that the behavior has the potential to trigger a conflict with others. A medium score (4-7) means that the behavior risks making you look inelegant and unsophisticated. More about the Rude Index and its methodology here.
Avoid the worst chopsticks etiquette mistakes.
- 9/10. Sticking chopsticks into your food.
- 8/10. Gesticulating with chopsticks in your hand.
- 8/10. Rubbing chopsticks together.
- 7/10. Holding chopsticks in an incorrect way.
- 6/10. Resting chopsticks on the table.
Sources
- Effects of shape and operation of chopsticks on food-serving performance: pubmed.ncbi.nlm.nih.gov