OK, as promised, a posting on general blacksmithing. Please keep in mind these are techniques I used to learn and still use to 'warm up' when I have been away for a while. Your mileage will vary.
Let's start with the hammer. The hammer is the blacksmith's primary tool. The hammer is used to apply localized force to move and reshape the metal that is being worked.
Start with a short handled hammer, or 'choke up' on the handle. The handle should be smooth and just large enough around that your fingers close around it comfortably. Hold the hammer loosely. The thumb, web, forefinger and middle finger should be the tension providers, creating a circle of light pressure. This circle of pressure should be just tight enough to keep the hammer from sliding out of the hand.
With the hammer held in this fashion, stand comfortably at the anvil, with your feet about shoulder width apart. I find that I am comfortable standing slightly in front of the anvil, the tip of the horn pointing towards the inside of my left thigh. This puts my body at an angle to the face of the anvil of 30 to 60 degrees. This angle will change depending upon what I am working on. The face of the anvil should be at a level that the flat face of the hammer is flat on the anvil surface with your arm comfortably extended.
When using the hammer to strike,do not 'push' the hammer into the project. Instead coil the hammer hand up, rolling your arm up. The head of the hammer will be near the ear. Let the hammer gently fall, unrolling your arm in the process, the hammer will accelerate as the hand lets the hammer 'snap' into the project. Use the recoil from the blow to roll the arm up again. This technique will help you hammer all day long with less wear and tear on your shoulder and elbow.
To test the 'square' of your blows, the anvil height and how to 'adjust' for different thicknesses of material, take a couple of pieces of soft wood, such as pine to the anvil and hammer into them. Just a few strikes will do. Now look at the impression made by the hammer face. Is it 'tipped' as in one side is deeper into the wood than another. This will tell you if you are dropping or lifting your shoulder and if your wrist is straight.
Use these steps to help adjust how you hammer and enjoy.