This is not going to be one of those worn-out lists of things that people put in engagement-harvesting videos (be quiet on Japanese trains, but it’s ok to slurp your noodles audibly). Instead, here are just a few suggestions that, if followed, will save some trouble and potentially make a business visit to Japan more productive.
Bring business cards.
Upon meeting a Japanese business person for the first time, you should present your business card. I cannot count the number of occasions I have seen foreigners come here expecting to have business meetings, but not having any (or sufficient numbers of) buiness cards.
Bring sufficient cash.
I have on numerous occasions had to foot the bill (albeit paid later when invoiced along with services) for things like taxis in Japan. Japan is moving towards a cashless economy, but is not yet there, and this becomes more obvious as you move out of the large urban areas.
If you are in Japan as the seller of products or services, act accordingly, not like you are a tourist to be catered to.
This is a difficult problem, particularly because of the language problem. If you are not functional in Japanese and are visiting a potential Japanese client, even though you should be in a position of selling, very often the Japanese client will treat you as a guest. This is not to your advantage, considering you are asking them to do something like purchase products or services you sell.
One example is that some foreigners come here thinking they are going to treat their potential client to dinner, only to find that the other side has already arranged things, making the foreigner to picking up the tab not only difficult, but also rather defeating or embarrassing for the Japanese party.