First of all, due to the shape of sushi itself, there are many rules on how to put sushi into your mouth.
Don't grab sushi hard, but handle it gently, so that it won't come apart. If you want to use chopsticks to clamp, you should pay attention to the clamp, and it is easy to spread if you clamp it sideways.
Serious sushi restaurants have soy sauce and ginger slices, and there are many rules on how to use them.
Soy sauce is not for you to dip in, but to brush on sushi. Never dip in soy sauce with sushi in your hand, it will be embarrassing. Just brush the soy sauce on the surface of sushi, and don't touch the rice, which will destroy the overall taste of sushi.
Ginger slices are not eaten with sushi. Their function is to "relieve boredom" and avoid the numbness of taste caused by eating too much sushi.
The most important thing to eat sushi is to finish it in one bite. If something is not big, there is no need to taste it in one bite. This will only make others think that you are a "terrapin", and the sushi will be scattered and it will not look good.
Specialized sushi restaurants have a very unique tradition, that is, the "ten-second principle".
The newly-made sushi is in front of you. If you haven't started it for more than ten seconds, then you won't have the right to enjoy it. Whether this principle is strict or not, don't try it casually.
There is another rule for eating sushi, which you should have noticed in TV dramas. Many Japanese dishes are common.
Sushi should be tasted from light to heavy and enjoy the gradual feeling. Just eat other sushi first, and sweet sushi is best eaten last.