In reply to Jon de Leyser:
i presume the landowner knows you want to bang stakes in?
If so great, I would put 3 or 4 stakes in a good 10m back from the edge, then you can equalised 2 or 3 of them where you descend potential routes. If it's a narrow crag, then put two or three in a row, a metre or so apart and equalise like you might snow stakes. Anything metal and strong going down up to a metre deep will work, just leave enough sticking up so folk can easily see it and you don't make a trip hazard near the edge.
You may once you have developed the crag want stakes in more specific places etc.. also consider crag height if it's loose and you need to put stakes further back.. You need to be able to climb the route, then have enough rope to reach the stake and get back to the crag top on a 50m rope.