So yes, some small sign would be good to warn off those who expect you to be jolly. Wearing all black is an option, although ...

The idea of wearing jeans and T-shirts as if everything is normal feels bizarre. Is there a way to signal mourning? A black ...

However, players can often be seen wearing a plain black armband on their jerseys too. This is used as a sign of mourning and can be worn by every player on the team, as well as officials.