I think REALLY good siganage and maps are a key. Maps can have the rules well documented on the back.
Trail markings should clearly define the trail corridor on BOTH side of the trail, especially when there are multiple lines available. If you get to run the easywild at Elbe, you'll see what I mean. There is never a spot where you don't know what is and is not part of the trail. Unfortunately all the trail head markings have been destroyed but once you're on the trail, it's very clear.
Any trail intersection should also be VERY clearly marked with good signage like road signs. It's very easy to get off on the wrong track with completely good intentions.