You could put them high but I usually put them on a level with the animal.That way,the animal can be far or close and you still get a picture.If the camera is pointed down,you have to be right on the money.
I try to point mine North when possible.
Another very important point is to not have any branches or weeds in front of the camera,within range,that can wave in the wind.These will trigger the camera on a windy day.
A weed growing up in front of the camera could also cause the camera to auto focus on the weed-not the animal.
For the same reasons,don't attach the camera to a flimsy sapling that may also move with the wind.
I have bought silk,Fall leaves from a craft store and used them to camouflage the cameras.Kind of like a leafy suit.I made some "rubber bands" out of 1/4" elastic,stapled the leaves to the band and put that around my camera housing.It was easy to remove and put back on when checking the camera.Just keep the leaves away from the lense.The 3-D leaf affect is a little better than just a camo pattern.