1. Only order sushi or sashimi. Rolls are the Big Mac of the sushi world. And while the Japanese adore McDonald's a California Roll will in no way endear you to the Chef. And you're at bar to suck up to the Chef.
2. Wasabi is only for sashimi! Because sashimi is fish unadorned, it's ok to stir wasabi into a little soy sauce for dipping. Sushi, however, will already have the "exact right amount' of wasabi between the rice and the fish. These guys are armed with eons of prejudice and very sharp knives so please don't be foolish.
3. In the same vein, when eating sushi, only dip the fish in soy sauce never the rice. I'm sorry but their sushi rice recipes are as revered as the mysteries of the Japanese Imperial Family's lineage and they don't like round eyes messing with either.
4. Always offer to buy the Chef a drink. This action will help to alleviate a multitude of sins and he'll be honored.
5. And finally, saké is ok with sashimi, and it's also ok before your sushi, but not with the sushi. Only beer or tea. Saké is made from rice and for whatever reason the Japanese are NOT down with eating rice and drinking rice at the same time.
These mistakes are the equivalent of salting your food before tasting in a French restaurant. But while the French are usually half in the bag or feeling up a skirt somewhere, the Japanese are watching for the slightest breach of etiquette and they never forget, in part probably, cuz fish is brain food. Just know the militarism of a tried and true Sushi Chef makes the frothing psychosis of a French Cook seem downright fun loving.
Good luck, dont' be foolish and next time we'll talk noodles. Your assignment is to watch the terrific Tampopo and get to slurping.