A little of both. I do research online and find like old maps and directions from forum posts and stuff like that to find specific spots that are already known to others. Once you go out to a few spots and know what the desirable stuff looks like you'll start to notice it when you see it even when you're not in an area specifically known for having the material. I collect a lot of agate nodules that grew in amygdaloidal basalt and they have a very distinct look on the outside. So once I went to a few places that have tons of them all over now I notice them when I'm walking around in the hills and stuff. Luckily for me I live near the greater Los Angeles area which has lots of relatively accessible areas where you could spend all day digging up bloodstones and geodes and selenite and howlite and opal and even fossils