Survival situation: a situation in which your life is in actual danger
First (and most important) part of survival is DON'T END UP IN THAT SITUATION!
Take precautions. When paddling, put on your PFD before you get on the water and take it off AFTER you leave the water. Don't go into choppy water, rapids, dangerous zones unless you have first planned your way through and second, planned your escape if it all goes sideways.
When hiking/backpacking, know you area. Get a map, familiarize yourself with the trails, camping areas, ranger stations, roads, fire breaks, etc BEFORE you go in. Plan where you are going, keep track of where you are, and have an escape plan.
Watch for dangers. Train yourself to look for snakes and know how to identify the venomous species in your area. Look for spiders and scorpions. Take the headphones out and listen for rushing water or thunder. People listening to ipods get swept away in flash floods because they couldn't hear the water rushing in on them from behind. Keep your eyes open for bears, cougars, wild dogs, pissed off turkeys, whatever. AVOID DANGER.
Sniff for smoke and listen for gunshots or animal calls. Don't wander into a hunting area or a controlled burn area.
The best way to survive is to never end up in a survival situation in the first place. The most powerful computer in the world is right underneath your hat. Use it.
Learn and practice some survival techniques when you can, but prevention is by far the best route. It's like driving safe and wearing a seatbelt. You should know how to get out of a skid, but it's best to avoid hydroplaning.