I cannot emphasize enough. It will help with the learning curve greatly if you do a search and watch a bunch of blacksmithing videos now while they still exist.
Seeing the transformation of a piece of metal and how the blacksmith did it will help you greatly. Then after the SHTF you can use these pages to jar your memory of how it is done.
When you need to have a flat piece of metal cut instead of using a saw, simply heat the metal to working temperature and use a cutting Hardy tool to cut the metal. The cut will not be as pretty as if it was made with a saw. That is expected and OK. After the cut is made you work the metal back into a less mangled look with your hammer.
The color of the metal changes as it is heated and this color is important for indicating the temperature and workability of the metal. As iron heats to higher temperatures, it first glows red, then orange, yellow, and finally white. The ideal heat for most forging is the bright yellowish-orange color. Because being able to easily identify how hot the iron is bright light can actually be a hindrance to the blacksmith. Low light conditions are actually preferred, but not to the point that it is so dark that you can't easily see what you are doing.
When making multiple bends in a piece of metal it is usually best to work your way from the end towards the center.
When making knives and other things after the object is made you will need to temper it. Heat it until a magnet will no longer stick to it. That is the curie temperature. For steel this will be a bright red color. Then to while hot submerge it in oil to cool it fast. This locks in the atom structure. Now the metal is hard, but brittle. Next step is you heat it again, but not as hot. Steel would need to be a slight yellow temperature. Heat it slowly by putting the metal close, but not actually in your fire. After it gets that yellowish color, about 400F (204C), quench it again in the oil. If making a knife or blade it is now ready to take an edge.
Cutting a slot in a piece of metal. Use a chisel to cut through. Or nearly double the metal over on itself and use a cutting Hardy tool to cut a slit from the doubled in inward. Make the slit half as long as you want the final slit. Now simply straighten the metal and you have your slit of the correct length.
Use a heavy hammer when you start shaping a piece of metal. Then as you near the desired outcome switch to a lighter hammer for finer control.
When cutting with a Hardy tool it is not always necessary to cut the metal completely in to two pieces with the Hardy tool. Get a good cut going and then simply work the metal back and forth with pliers to finish the break.
When drawing out metal (making it wider) when striking the edge, don't strike straight down but instead put strike the metal in such a way that you hammer strikes while moving in a direction not only down but also away from the center of the metal.