What are some rules of Slack etiquette?

Slack etiquette varies greatly between different workplaces, so it's hard to give general guidelines. However, most workplaces that use Slack do have some common rules. For example, if you are writing a message during non-work hours, it's better to schedule it to be sent during work hours. If you are responding to a message, it's better to do it in a threaded reply than by starting a new thread.