When it comes to sushi, there are three additions that usually accompany the plate: wasabi, soy sauce (shoyu) and pickled ginger (gari).
Wasabi does not necessarily need to be added to everything, especially nigiri, which is usually already seasoned. And unless you are dining on sashimi—thinly sliced fish without rice—it is not custom to mix wasabi and soy sauce.
Pickled ginger is primarily used as a palate cleanser between bites. It can also be used as a means to add soy sauce to the roll by simply brushing it with chopsticks.
Know the Names
Maki, meaning "roll" in Japanese, is the root for what most commonly refer to as a sushi roll.
Nigri is a hand-formed sushi using a mound of rice pressed into a rectangle by the chef’s palms and topped with neta (common toppings include salmon, tuna and shrimp).
Sashimi is technically not sushi but often finds itself on the menu along with nigri and maki. Consisting of sliced raw fish served without rice, shashimi is a chopsticks-only dining style.
How to Eat
When eating sushi, don’t be afraid to use your hands. Nigri is traditionally eaten with your fingers. If using soy sauce, dip fish-side down. If it is too difficult to invert the sushi, baste the soy sauce on the topping using the ginger.
Rolled sushi, makizushi, is also primarily a finger-food, though if it is a sauced roll, chopsticks are acceptable. Proper sushi etiquette would have diners using their fingers, so if the chef—itamae—is especially attentive and traditionally trained, use your hands.
Sashimi is always eaten with chopsticks.
If you are feeling brave and are up for just about any ingredient, let the chef, itamae, help you with your choice. Called omakase, this essentially allows chefs to choose what they think is particularly good that day and serve you until you are finished. If you have an aversion to a certain fish or style, it is best to avoid this dining option.