For gliding I was taught size, shape, slope, surface, stock, obStructions. Maybe there was a 7th S!
Fences across fields often show themselves in a subtle colour change, posts for phone cables or a single power cable by a little circle round the base. Don't fly between trees on the approach if at all possible as the trees can hide posts carrying cables.
If the field is big enough (think East Anglia) you can get away with a downwind landing, and top choice in the glider world for landing is a stubble field. The farmer doesn't take a very expensive combing through a field with a dodgy surface.
Permanant pasture isn't good as it's often rough, but if it's all you can find...
(edit) I am a map freak so I always have a good look at the map (OS, not just the 1/2 mil) and Google Earth before I (try to) go anywhere new, to get a feel for where it might be hard to find a field and where it might be easier. However in a glider I have a good idea I'm going to need a field for a long time in advance.
Last edited by cats_five; 28th November 2012 at 17:43.