Nail head, meet hammer. And there are some things to look for just like finding random deer in the woods. Plowed fields obviously, but also in those plowed fields along or near a waterway and maybe on a slight raised area. If the soil in the area is light colored, that raised area in the plowed field along the creek may have darker ground. If so, it could be an old village site. If that's so, you will probably find a lot of broken or inferior heads(knapping mishaps), knapping flakes scattered heavily, and lots of broken pottery pieces too. Drills, grinding stones, hooks, pestles n mortars, beads, etc. may be laying around. After the first rain once the field has been plowed is a great time to spot arrowheads because the rocks, pottery and such will often be laying smack dab on top of the ground and freshly washed at that.