~For fire starter, I usually grab some birch bark when I see it, and put it in my bag or pocket. One of the amazing things about birch bark is it will light after being plunged in water; just wipe the excess moisture and get busy with it as tinder. Another great one (and unexpected like Doritos) is dried citrus peel. There are volatile oils in the peel that spark and crackle when lit (similar to birch bark); they can also be used for a vitamin C rich tea.
~A simple and quick knife edge can be made by taking a large round rock and smacking it on another (being careful to shield your eyes). You might have to hurl it at a stone to break it. The disk that comes off will likely have a serviceable edge for cutting or sawing various things on a short term basis. A large round stone will produce quite a few blades.
~The best survival water purification in my opinion, is boiling. The following survival hack requires multiple steps; all fairly easy with some perseverance. It is fun, so it's a cool thing to do when you don't NEED to do it.
1.) Toss lots of small stones (not from a creek or other water area as these tend to trap water which becomes steam and explode) into the fire to heat up. Get them really hot.
2.) A simple bowl can be produced by placing a hot coal on an appropriate piece of
wood (right size/non toxic). Blow on the coal (gently so as not to blow the coal off the wood-practice you'll get it, and it gets easier fast). Char and coals are produced on the wood surface. Scrap the charred area with your homemade stone disk knife, sharp rock, or actual knife. The bowl is started. Repeat until you have a servicable bowl. Go fill it with your water.
3.) Once the bowl is full of water, get a couple of sticks to use as chopsticks and pick some of those super hot stones you have been heating out of the fire. Add these to water that you have put in your fireside bowl, until you get the water to boil, removing them as their heat is lost to the water. Continue to replace stones until the water boils for long
enough to satisfactorily kill bacteria. Some say ten minutes, other say less (after all it was killing all kinds of bacteria as it got up to boiling too). As soon as it has killed the bacteria carefully set it aside where you will not spill it. Go gather some more
firewood. When you return it will be cool enough to drink. Drink no more than a couple cups (half litre) at a time, so that your stomach doesn't get depleted of electrolytes. As soon as the water is done, boil more to drink later. Making a second bowl will allow continuous water purification.
*The second most important survival hack is to give yourself things to do. (build a fire/build a figure 4 trap like the one in the pic above---not as easy as it looks, but simple enough~practice!) This allows the mind to be occupied and accomplishing things which are great; the opposite: a mind that can turn on you and you end up not being productive at all- a vicious circle that can kill you. Build a fire. And if you can't then Build a
shelter. Insulate your clothing with dry material. If you can get a fire going, the afterwards find dry firewood. Etc. There is always something to do.
*The number one survival hack is always to keep calm. If panic sets in, stop it. Calm yourself down. Talk to yourself (don't just think, talk it out). Think of things to do {out loud}. Be positive. Be productive.
