Reddit mentions of US Army Survival Manual: FM 21-76

To add to what Ryan said, there are also a bunch of good books on the subject, most of which can be found for free.

John 'Lofty' Wiseman's SAS Survival Handbook is extremely comprehensive (around 600 pages) and very information-dense.

The US Army Survival Manual is also pretty good, but it's not as comprehensive or detailed as Wiseman's book.

Although it's more of a bushcraft book, Mors Kochanski's Bushcraft is extremely well done. His descriptions are easy to read, but fairly comprehensive, and are paired with detailed sketches and pictures.

Mainly, just go out and practice. You're already a capable outdoorsman, so it shouldn't be too much of a hassle. If you wanna take courses, just search around for courses near where you are, or maybe look at something like NOLS. Hope that's helpful.

SAS Survival Handbook

US Army Survival Manual: FM 21-76

UST Learn & Live Outdoor Skills

Other things:

• Silver space blanket (helps in all types of weather)
  
• 250' of parachord (side note: make one of those survival bracelets . It gives you about 12' that is always on your wrist)
  
• Survival Tin (nice little back up: SAS Survival Tin)
  
• WetFire fire starters (stuff is awesome. Little piece all you need to start a fire )
  
• Monocular
  
• Signal Mirror / Whistle
  
• Multi-tool (SOG PowerAssist)
  
• Hand chainsaw (Here)
  
• Army Survival Book (FS 21-76)
  
  EDIT: If I get a chance I'll take a picture of my survival pack. People think I'm crazy but never hurts to be prepared.

Perhaps something like The Army Survival Manual? I know it has first aid, foraging, methods of getting water, and ways to build shelter.

Forgot to also mention, I have about 3 copies of this in various locations. Incredible resource that has been of use plenty of times. Once, stranded on Short Key during a monster storm it was used as kindling for a fire (one of the reasons it is printed on untreated paper).
Seriously, go buy a copy now.

I'd switch out the Catcher in the Rye for this I have a copy and it has some real useful information. And no, it's not just for combat scenarios.

Purchase the US Army Survival Manual. It's full of information about first aid, tracking and trapping animals, navigating, improvised shelters and water collection methods. I keep a copy of this in my backpacking pack at all times.

Also, make and keep a bug out bag (again, this is my backpacking pack). It should contain basic survival items like a water filtration and purification system, first aid kit, versatile clothing, sewing kit, non perishable food, a weapon and appropriate ammo, a good knife, some para cord, topographic maps of the area you intend to retreat to and planned route to escape the city if you live in one.

As for being part of a group, develop a skill that is valuable to other survivalists. A simple skill that will come in handy would be sewing. Clothes and shoes will need constant maintenance in the wilderness. Learning some basic blacksmithing and would be excellent for making tools. Understanding the basic mechanics of a firearm and how to repair one would also be immensely valuable. Take at least take a CPR & First Aid course. Learn how to navigate in the wilderness and how to predict weather patterns.