Let me start by telling you the story of two Johns.
John number one went on a day hike with a couple of friends in the Cascade Mountains about an hour from Seattle. He somehow got separated from his buddies and became lost. John was dressed in casual cloths for a warm weather day hike and had nothing but a lunch with him. He spent three days in those mountains and luckily made it out to tell the story.
John number two, a friend of John number one, was much better prepared when he went afield. He always had a compass, a GPS, fire starting equipment and some rope. He knew the dangers of getting lost. John went to Alaska on a moose hunt and when a member of his party shot and wounded a moose, he took off through the woods armed with nothing but a camcorder. Oh yes, he had the survival equipment in his pack.... back on the four-wheeler. A lot of good it did him there. He didn't even have a gun to signal with. Number two spent a few hours wandering around in Alaska before his buddies realized he was lost and "they" fired some shots so he knew which way to go.
John number one didn't have a survival kit. John number two had one but didn't bother taking it with him.
My tip, everyone should be prepared for the worst when you go into the woods, especially when you're in unfamiliar territory. I have put together a backpack survival kit. I knew it had to be small enought that I didn't leave it in the truck, yet complete enough to get me through. I would suggest that if you don't have one, you make yourself one or go out and buy a commercially prepared one. You may never need to use it, but if you do, it could save your life.
One of the hardest parts of my kit was to find a container. I searched long and hard before finding a company that carried just what I wanted. Since I helped a boy scout troop make these, I ordered several dozen of them. They are small, round, metal containers 3 and 3/4 inches in diameter and 2 and 1/2 inches high. They are large enough to pack what I want in them, yet small enough to put in my backpack and leave it there always. You can find these containers at: http://www.papermart.com/Product%20Pages/Product.aspx?GroupID=14267&SubGroupID=14268&ParentGroupID=19037#14268  You have to buy them by the case so you might want to find some other guys to go in with you. They will run about $1 each.
Here's what I put in mine.... Waterproof matches, Fire starter sticks, a small candle, some water purifying tablets, a band-aid or two, plastic bag for carrying water or collecting things, one or two chicken and beef cubes, a couple of tea bags, some salt and pepper, a couple of pieces of hard candy, a small pocket knife, some string or cord, 15 feet of fluorescent plastic tape, some aluminum foil, fishing line with some hooks and sinkers, a whistle, compass, several small pieces of paper, a pencil, a piece of chalk, a couple of push tacks, a length of wire, a signal mirror, a small flashlight and a complete set of survival instructions. You may wonder how all this fits in my small metal container, but it does. I even include a couple of Bible verses to keep me calm.
I drill small holes near the top of the metal container and include a small piece of wire so you can put a bail handle on the can and use it to cook in.
Bottom line is to make it big enough to carry what you want but small enough that YOU WILL CARRY IT. I believe the most important items you can put in are good fire starting pieces.
I hope this helps you be better prepared when you go into the woods. As I said earlier, it's a piece of equipment that you hope you'll never use, but if you need it, it can save your life.
Oh, by the way, I am John number two.