I believe the method should be, as much as possible, to do interesting running exercises while orienteering. Intervals, Fartlek, Tempo- almost any form of athletic exercise can be done while concentrating on finding O-controls.
This is what I did today: 20 km running that included 6 km of Fartlek-orienteering. This can be done in various ways (I once ran a course using a timer to change my pace every minute without any connection to the course). Today I ran one leg slowly (5:00 min/km) and the other sprinting.
I'm trying to return to shape athletic-wise and orienteering-wise and this seemed to me like a good start.
I'm not sure if what I did today can be counted as very difficult orienteering, but unfortunately as a city dweller these are 2 of the closest maps I have to home.
Map: Four seasons park
Mapmaker: Sergey Yakimov
Map: Park Ra'anana
Mapmaker: Eshel Lipman & Oded Verbin
(Notice the Maze in the bottom left)