I would say one of the best things to do is not give no warnings for tresspassers.... The signs should be their first warning....Press charges right off the bat and eventually the word will get out and help some with the problem...Make surprise visits up there occasionally if possible during the deer season and travel the roads around your property to see if any vehicles are parked there and right down their plate no. ...Then if you do encounter someone and they take off you got some kind of info on them...Not all the time but sometimes..But, I think theywilllearn the diffinition of NO Tresspass after laying down a few 100$ bills....