Just to add something not to specific, you might not have considered looking at reports from archeology and current tribes of hunter/gatherer types. Learning a bit from them has helped me, as I often retreat to my woody spot to work on building a homestead out there. My longer stints almost always go badly after about a month.
Water purification and a reliable source is a must. Running water is best, as river and creek beds will do a lot of the filtering for you. You can also boil water in just about anything, even a paper bag, believe it or not, but I wouldn't recommend that. Spring is obviously the best time to survive, but after a month in the woods I came out with Lyme disease, which was not a fun time at all. Anything can kill you out there, and it's usually not the bears and wildcats that worry me. It's the smaller critters that are looking for someone to cuddle with at night.
Anyone quoting the 3 weeks without food thing, I encourage you to try that in the wilderness and let me know how it goes. You need calories, and you will burn a lot in the brush. Larger people that have high metabolisms (like weight lifters) will suffer fatigue the fastest. If you aren't getting enough energy producing food, you are going to be tired, unmotivated, and probably riddled with headaches. To that note, I recently discovered that a LOT of protein and calories in hunter/gatherer tribes came from insects, which after being out there long enough, is a revelation you will have sooner or later. They're easy to catch, and they are abundant most of the year. Pick a shady spot, and they will come to you. Depending on the terrain, snakes can be easy prey. If you know how to set simple traps, then smaller furry critters are pretty easy to catch. I think the army manual has a long section on that topic.
Temperatures drop at night, and it gets hot during the day. This varies, but expect some drastic changes throughout most of the year in most places. Shelter from the elements is a thing. Most of my experience until I got a simple cabin constructed was sweat all day, freeze at night.
Maybe there's a couple of nuggets you can dig out of this post, but definitely look into the bushmen of Africa, and maybe South American and Australian tribes that research has been done on. The best survival experts aren't selling plastic "survival" tools on TV. They're out there living in the brush.