I usally try to teach my "new" actors the concept of "social distances & space" . It's a pretty basic concept that is proven to work, the hard part is trying to get them to understand who & when to invade on. We also try to pair them with a veteran actor for their first few nights. Some people "get it" faster than others, but once they understand the concept it's easer to move on to things like scare timing,body & head movement,& dialog, or in some cases no dialog.
All of those points are covered in my "Boo Camp" training seminar, plus a whole lot more...