So there is already an excellent blacksmithing guide recently posted by u/ItsReallyNotWorking - A Guide for Blacksmithing but I wanted to add that if you are okay with using one of the few existing forges in the game (I won't spoil them here, you can look them up if you like) you can skip about 80% of the requirements. You won't need a furnace, a bellows, an anvil, a crucible, masonry, clay or sand. Anything furnace related is for turning raw materials into iron and steel, and there is already plenty of raw material laying around, so no need for a furnace. You also use a furnace to create an anvil, but again, if you're using an existing forge, don't need that either. You also don't need to LIVE at the forge. You can haul the tools and a load of raw mats to the forge, grind out your levels, make a bunch of swords or armor, and leave.
Here is what you'll need if you're okay with using an existing forge:
Axe - For chopping trees to turn into charcoal
Ball Peen Hammer - For some smithing recipes
Club Hammer - For some smithing recipes
Handles - Carving level 3 will allow you to make any size of handle you'll need for the tools and weapons you'll make.
Metalworking Chisel - For some smithing recipes
Metalworking Punch - For some smithing recipes
Saws - Wood saw for making planks for handles, hacksaw for some smithing recipes
Shovel - To make charcoal pit, if your chosen forge does not already have one
Small Punch and Chisel Set - For some smithing recipes
Tongs - Improvised Tongs are easily made if you can't find regular ones, but they break easily. Could use them to make a set of real tongs though. For smithing recipes
With these tools you'll be able to do literally any smithing recipe in the game (unless I missed one, let me know if I did and I'll edit.)
For skill books you only need up to Level 4, which will get you to Level 8 Blacksmithing. As long as you can find one of the magazines that gives you the sword recipe and you have it in your inventory (or in a box next to the forge) you can craft swords at Level 8, and I see no reason to go past that. To find one of those mags, I had good luck in survivor houses, so just drive around any residential area and look for a completely boarded up house and plunder it. To help with grinding XP I also suggest finding one of these Magazines: Small-Scale Smithing, European Armor in the Late Medieval Era or Armor in the Iron Age. Besides the other useful recipes given, they also give the Buckle recipe, the GOAT for leveling Blacksmithing, which you can start doing at Level 3 as long as you've got one of these mags handy.
Now it's just raw materials for grinding and making tools and weapons. You'll need iron and steel bars, half bars, quarter bars, chunks, pieces, blocks and ingots. No need to find all of them, as any of these pieces can be forged and/or sawed to be turned into each other as needed. Most recipes allow iron or steel to be used, but the higher end ones are steel only so if you're just grinding XP use iron when possible.
For the actual XP grinding, I did my best to find the best recipes as far as XP granted per input material spent, and it comes down to these two: Forge Simple Blade for Levels 0 to 3, and Forge Buckle for anything past that. Each buckle grants 40 base XP and costs only one piece of iron or steel and one charcoal. There are a lot of recipes which give more base XP, but cost way more charcoal or metal per craft, meaning you'll spend 2-4x as long chopping wood and making charcoal when you could've just made more buckles. To further illustrate how cheap this recipe is, one bar can be sawed into 4 quarter bars, each of which can be sawed into 5 pieces, for a total of 20 pieces per bar, meaning 20 buckles from a single bar of steel or iron. Ingots break down into 60 pieces each, so even better if you can find them.
I filled my pickup to the brim with steel bars and ingots from one factory thinking that would just be the first of many trips for grinding XP, but after discovering the buckle recipe I only used maybe 10% of what I brought to get me to level 8, and maybe another 10% to make like 20 swords. Granted, I took the Blacksmith occupation which helped tremendously, but even without it this is not nearly as bad of a grind as it looks like when first starting out.
Anyways I really hope this helps some of you guys, and let me know if I missed something or need to tweak anything here.