Probably the best wilderness adventure advice I found in Dungeon Fantasy 16: Wilderness Adventures was pretty simple:
Show them the map.
I put down a map of the swamp of the Cold Fens (at least the wet, everglades-y waterways portion they are in) and cover up the bits they can't see. Then I move and reveal it as they go. I leave it revealed from then on, so exploration always widens their (wholly accurate) map.
All they know is, they can still get lost (from bad rolls or bad decisions), they still don't know what happens in any given spot on the map if they go there. They still don't have fully actionable knowledge about the entirety of the map. But they have enough to make clear decisions.
It makes it easier to run as the GM, almost as easy as (actually maybe easier than) dungeon adventuring. It's also exciting. The players get into it more. They are more active in marking the map and making decisions. Everyone can see at a glance just how nasty the surroundings are, and decide based on it. The only thing that could make it better is if I could draw pictures of the swamp I see in my head when I'm describing the place.
You can see this in Delta's sandbox games, too. Having the whole map in front of you means choosing your path with more clarity, but it doesn't reduce the mystery of what is to come.
I highly recommend doing this with wildness adventures - show them the map. Let them find out as they go what's in the dark places and ruins on it, but spare yourself and them the hassle of describing a wilderness.