Look for open fields. I live in Idaho, and we have kestrels everywhere, especially along the highway where homes have at least an acre of property, or full agricultural land, although I see them in town, usually near open lots with wild weeds growing so they can find bugs and mice. Just the other day, I had a kestrel flying alongside the car in the middle of town, in a residential neighborhood with a young starling in his claws! Kestrels will often hover over a field, or sit on power/ telephone lines watching the field below. Other hawks, like red-tails will perch in a tree (often a dead one, so they have an unobstructed view) overlooking a field. Or, watch for high, slowly spiraling forms.