I site my snares where i can see runs entering or leaving cover (brambles etc)
this provides a natural bottle neck and the hole in the cover provides the exact placement of the snare
i usually look for places which i can see a small hollow just inside the brambles just behind the hole where the run appears where the rabbit can stop and watch the open ground before venturing out (as these seem to be the prefured runs for rabbits and those most used)
or
places where they travel from cover to cover (as this is usually done quickly and they are focused on the other side)
always with the loop a fist wide and four fingers off the ground I have also taken up Ed's practice of always using guides (small sticks to ensure that the rabit does not travel around the snare)
this is one of Ed's setups
also note in the picture that Ed's snares end with a triangular section where they are tied to the tree, this adds stiffness and support tothe snare to prevent it from drooping (another tip that i have adopted from Ed)
the placment is by far the most important part of laying a snare though in the picture below the snare has no guide sticks, no triange where its anchored (in fact it has no cord to tie on the wire is twisted directly around the anchor) it doent even have an eyelet, its just a piece of six strand brass wire yet this snare is in a good position and caught a rabbit each time it was set (three rabbits in total)
be sure that before you start snaring you fully understand the law and i recommend geting somone with experiance to take you out for your first few trips