Once you have decided where to set up your campsite you must decide where to set up a tent. The factors to consider are season, temperature and condition of the ground.
The first to consider is the time of year and temperature. If it is summer and hot you should consider setting your tent up in the shade but still accessible to a breeze. The breeze will help keep you comfortable and reduce flying bugs such as flies and mosquitoes.
If it is winter or cooler temperatures you will want to set your tent in the sun. This will keep you warmer. To reduce the chill factor, try to find a sheltered area to block the wind. Annoying insects should not be a problem in cooler temperatures. While winds may change directions as low and high pressure systems move, try to go by the prevailing winds. If you are on the side of a mountain or large hill, warm air rises and cooler air settles. Closer to the earth's poles the jet stream moves from west to east while closer to the equator the trade wind flows east to west.
The type of ground should also be considered. Try to find a spot as level as possible. If you sleep on a slope you tend to slide into or out of your sleeping bag as you roll around. With your head uphill you will slide down into your bag. If your head is downhill you will slide out of your bag. If you sleep across the slope you will roll downhill. This could be a good thing depending on who you are sharing your tent with.
Also consider a low lying area. If the leaves seem to be flat and compressed the area could be a collecting spot for rain water. I would find another spot. Also look for a rocky or sandy strip. This could be a dried river or stream. It can remain dry for a few days after a rain but can fill quickly a couple of days after a storm. Water takes time to filter down tributaries or seep into the ground raising the water table to the point of spilling into the dry bed.
Once you have figurged out where to set up a tent you have to decide how to set up a campsite.