As a game master, I try to tell my players as much as I can. If I think there is a bit of knowlegdge that is common to a group of characters, I tell them. Some game masters would say I tell them too much. The reason I err on the side of too much information, is when a character dies or has some severe downside, it is almost always caused by something that I have given plenty of warning about. If the player decides to risk it, then that’s on them.

Also, I hold back. I don’t tell them everything. There are surprises, usually things that are not immediately dangerous. The biggest no no is explaining things to your players after the fact. Never do this. You are a magician performing an illusion. If you show them what is behind the curtain it loses its effect. Only tell them what their characters ought to know and be generous but keep secrets.