As far as Japan's ability to make money is concerned, some goods will be sold at the signing ceremony. In this case, it is best to sign for it after buying. As for whether there are any goods for sale, it depends on the news of the organizer. If there is a surrounding sale, the surrounding content will definitely be announced. If not, it is best to bring some related items, such as seiyuu postcards, magazine clippings, or the periphery of famous people. Of course, it is not kind to stick with cards.
It's ok to give gifts, that is to say, most cities (in the powder I know) usually give them to him when it's your turn to sign, and he will put them in a prepared carton, which is usually in his memory.
You'd better say a few words of support when signing, for example, I like the voice of XX Sang very much. I was very moved after listening to the role of XX Sang, and I will continue to support XX Sang and the like in the future, of course, in Japanese. Remember to thank you when I take it.
Go early. If it was just an autograph session, there would probably be no chairs. Of course, don't bring a small bench. Go early. Look at the venue and bring a fan or something. It is hot when people are crowded together.
In addition, you can actually take the cos test.