If the area had seen a lot of action No Man's Land would be full of broken and abandoned military equipment. After an attack No Man's Land would also contain a large number of bodies. Advances across No Man's Land was always very difficult. Not only did the soldiers have to avoid being shot or blown-up, they also had to cope with barbed-wire and water-filled, shell-holes.
Small groups of people were also sent out to get information about the enemy. These patrols would go out at night. They would have to crawl forward on their stomachs in an attempt to get close enough to find out what the enemy was up to.
If you were in the middle you could get stuck in barb wire or shot by the other people. They could also have mines and bombs planted.
No Man's Land contained a a lot of barbed wire. In the areas most likely to be attacked, there was barbed wire right before the front-line trenches. In some places the wire was more than a 100 feet deep.
Soldiers were only sometimes involved in a full-scale attack across No Man's Land. Although, men were sometimes ordered into No Man's Land to get information from the enemy.