The advice given is superb the only thing I would add is that if you go to where you know rats are ( look for greasey tracks ) in daylight look for any dark shaded areas around walls, fences,sheds and when you go there at night thats the most likeley place they will be so if you put any old food down around that area for a few days you should have great sport. Night vision helps but as was said in a earlier post low light left on for a few nights and a white board as a background works very well. thel also seem to like something smelly wrapped up in a tight ball of silver foil