My biggest mistakes have come from overconfidence. A few years back I stalked an Elk trying to make sure he was a legal shooter (spike only area). After several hours I ran out of daylight. My focus had been on the Elk I failed to pay much attention to my surroundings. It was a beautiful night and I was almost giddy with how much fun I had even though I didn't close the deal. I assumed camp was just over the ridge, due east of me. When I reached the ridge I didn't see camp but I did see another familiar looking ridge on the skyline. I hiked to it. It was there I realized I had no idea where I was.
I was well prepared which gave me confidence and allowed me to make good choices. We hunt solo from a base camp so no one was worried about my whereabouts. I knew I was on my own. I stopped, had a bite to eat and considered my options. I made the choice weighing the potential danger of walking cross country in unfamiliar territory in the dark and wanting to have enough energy left to build a shelter. My gear gave me confidence and so I was never in a desperate situation. I was able to find my way back in camp after some map study and a couple of good guesses. I restocked the food and water and went hunting again.
Having the ability to make a good shelter is my highest priority. I carry a poncho, garbage bags, cordage, and a folding saw at least. I also carry at least one extra layer of clothes not counting rain gear. I have had it all on at once and it can still be a little chilly if you aren't moving.
A fire is very comforting. I have a number of means to make it in my pack.
Having some food and water helps keep the spirits up. Some sort of water purification is needed.
A few methods of signaling is important too.
