The ability to work well with others and barter (skills, knowledge, equipment, food, etc.) will be the most effective addition to your survival skill base in any short, medium or long term survival situations involving more than one person.

Building these skills up is very important and the time to do them is now, not later when you are stuck in the wilderness. The idea of the "lone survivor" seems to make people think basic communications skills, leadership skills, and team building skills are not a necessary part of survival training.

At the end of my University training in outdoor education I was a member of a 94 day canoe expedition that conducted all its decision making using consensus. It was extremely hard paddling 10-12 hours per day, in sometimes very poor conditions, with weeks between food drops, no communications equipments (it was 1989), and having to continually work out consensus decisions. It did teach me how amazing it is to force one self to cooperate on a long-term basis and work with ones small team and those we came across in the wilderness and at settlements we paddled through.

We spent much more time before the expedition working on communications skills, decision making, and team building than on packing or preserving food for the trip. Every hour of team building practise paid off in spades along the way. The scary part is that 20 years later we are all still good friends and even scattered to different cities we meet at least once a year.