Yes I have a plat book and a phone book, but in person is best. You hit an off day asking, or you were in an area maybe too close to a big town, they get asked all the time and many say no unless you are in the right area. Make sure you let them know it will be just for the one day, that helps. You definatly have to have the ability to smooze people some. I Know guys that can't get permission in thier own back yard, but then I go ask the same person and I'm in. After asking thousands over the years it has helped. But if you keep pluging away and trying different aproaches politely, you will find some spots. Some are a waste of time that you can see with 10,000 no hunting signs, bird pens, dog kennels with fat labs in them ect, Just kidding on the lab thing guy's.
So look where there is none of that junk. There are thousands of them out there. Make sure to point out the specific spot and not every thing they own, never by the house at all, NEVER by the house. It may take some time for you to figure it out and what type of areas to avoid as a waste of time, but after that you will have a 90% success ratio on yes for today, today is the key. Or tomorrow or whatever day Only. Like I said I hunted a different place all but once and only was told no once, and he almost caved, I let him off the hook or he would have. The reason I hunted the same place twice is because me and T,O, flushed so dang many birds out there and never got one. this time there was close to a hundred and another guy and I got our limmit. But I won't go back and ask now there till next year, even though there is still several limmits out there. I have already spoted other places for the next couple hunts. So you see if you scout and ask first = good spot in the morning= done early enough to scout and ask for next time= same thing. Wish you luck.