Pretty much cold calling has worked for me, ive cards with my name, number, email and insurance company on them which definitely helps soften any scepticism or fear that im trying to scope a place for nefarious reasons

I do the exact same, got 100 cards from vistaprint for no money, give all me relevant details on it, then knock on doors and put in post boxes, keep em in me wallet and if I see any jeeps pulled in with sheep trailer on it then walk over and hand em one. Same with jockeys hand to them also as last thing they want is to have a horse break a leg in a rabbit hole.

I also advertise on farming forums, placed one in the farming sub here on boards for my area and have got a couple of call backs for foxing, once you get the foxing permission sure ya can just say to farmer can I do the rabbit(if land has em), crows, pigeons, magpies for them.

Getting in good with one farmer is worth handing out 100 cards as they will talk ya up to others they know and before long ya will have yourself a bit of land to shoot.