I always encourage everyone to look up, look around and look down when surveying a potential site. We look above us for things that could fall down and cause harm. We look around for hazards and protection from the elements. We look down for pests, drainage issues and other problems. The following simple guidelines can help you determine a good place to build a camp. But remember that there is no "perfect" campsite, so don't spend precious hours wandering around. Pick a fairly decent spot and start building.
Avoid places where rocks, leaning trees or large dead limbs could fall on your camp. Also watch out for hornet nests and other pests that might be right in the branches above you. If you are in an evergreen forest, plan a campfire spot that isn't under a bunch of dead, dry evergreen boughs. Your campfire could light these up and seriously escalate your survival emergency.
You should always look for structure that can protect your camp from the weather. Don't set up shop out in an open field or on a mountaintop where all the weather hits the camp.
But you don't want to become smothered either. Don't build your camp deep in a forest or jungle where it takes a long time to dry out and the air flow is poor. Try to find a place in between, like the eastern or southern edge of a forest or the south- or east-facing side of a hill or ridge. In looking around, we are also checking for hazards. Again, look for bees and other pests. While camping once, a friend and I set up camp after dark. It was a great campsite choice, or so we thought. In the morning, we noticed that the large tree on the edge of the campsite was heavily damaged. On closer inspection, the damage was the claw marks of a bear! We had camped at one of the bear's marking posts, to which they often return. Yikes! Look around before you set up camp.