When it comes to survival kits, I always think about the basic essentials first - your immediate priorities in a survival situation: First Aid, Shelter, Fire, Water, Signalling, and Food. To address these needs I carry a good first aid kit; a heatsheets emergency bivvy, heatsheets blanket, and some 550 parachute cord; spark-lite, strike anywhere matches in a bright orange waterproof case, bic lighter, magnesium and flint bar, candle (keep it in a baggie to avoid melting messes), tinder quik, fire starter sticks, some paper, and an ultra-thin piece of corrugated cardboard (check out your empty big mac box next time to see what I mean); a canteen or Nalgene water bottle with a stainless steel cup, water purification tablets, some coffee filters, and as a backup some heavy duty ziploc bags or baking bags; a good quality signal mirror, whistle, and some brightly colored bandannas (the bandannas are very useful for other things too); food bars of your choice (cereal bars and chewy granola bars are tops with us). Along with a knife and a sharpener, this is the stuff that should be kept on your person as Doug suggests, either in your pockets or on your belt (such as the knife and canteen). I also have a small led flashlight that I keep on my person (of course I hope to replace this with the doug ritter designed eq headlamp soon). Most of these items are in the Pocket Survival Pak I carry (check the contents list for the other items in it I have left out here like fishing kit, wire and duct tape), the other items ride in my other pockets (love those cargo pants and shorts). In addition, I have a small maxpedition pouch on my belt that carries some long term essentials and comfort items: a sewing kit with extra safety pins, some rubber bands and twisty ties, extra aluminum foil, wire saw, glasses repair kit, sunscreen, insect repellant, extra batteries, some tubing, and some carabiners and split rings. Yes it is tight but you can squeeze it all in there. If you can manage, you should also carry some rain gear (a good nylon raincoat and rain pants), some extra warm clothing (an extra sweater or jacket, gloves and a hat), larger compass (note the psp has a mini-compass), map of the area you are in, mess kit, some toilet paper and maybe some toiletries (toothbrush, toothpaste, cleansing towlette) as well. I usually put this and a folding saw in a daypack. As you might be able to tell, my kit is used in wooded areas with the potential for cold weather. Your kit should reflect the types of terrain you will be traveling in, the extremes of weather you will encounter and the amount and type of gear you want to carry. Make it as comprehensive as you can carry or as minimalist as you dare. As a final note, since you will be putting your own kit together, make sure you use QUALITY gear.