Forging is a very hands-on learning thing. One way to practice is get a can of Play-doh and make a wooden hammer. Roll the clay out to the shape of your starter bar and "forge" it with the hammer. You will learn how to make the clay move the direction you want. Try different shapes to the wooden hammer head ( make several). Each will move the material differently.
The biggest error in starting to forge is the thinking that hitting it harder will move the metal better. Controlled and well placed blows will do far better than pounding randomly. Learn to "push" and "pull" the metal by how you deliver the blow.
As said before, get it hot enough before wasting energy on hitting it. Five short heats between 2000 and 1600 will move more steel than 20 minutes of pounding on 1500F steel.
Work smarter, not harder. I know there are purists who say only forging should be done to shape a blade, but in reality, the blade will get its final shaping on a grinder. If the tip is at an angle, cut the bar at an angle to start with. If the blade will have a hidden tang, cut that out from the bar after forging the blade. Leave extra metal for shaping and flattening on the grinder. The old addage is "Forge to thick shape, grind thin to finish." Details like choils, deeply recessed ricassos ( bowies), etc. are better only roughly marked in the forging, and the shape refined on the grinder.
Until you get as much control as Sam Salvetti, don't wail at the billet with all your might. You will almost surely create divots and marks that will be too deep to grind out. Leaving a blade with dents and pock marks isn't the same as deliberately creating a blade with even brut-de-forge. Don't fall into the trap of saying, "It is so rough looking because I wanted it to be a primative knife." Knives have been well defined for centuries. Bad forging has not ever been an excuse for the final look in a blade.
Forget most of what you see on Forged in Fire. It is a constrained time competition, and the blades made have noting to do with a good finished blade and the best forging techniques. However, you can clearly see the difference when a peson who really knows how to forge is there with a person who is not. The final surface and shape are far superior.
I don't recomend making "practice" knives from mild steel, but I do recommend doing forging practice on it. Practice on drawing a bar wider, longer, tapering, upsetting, and fullering ( as in a smaller tang) can be done just fine on $10 worth of Home Depot steel. It is also good enough to practice your first forge welds on.
I used to give a student several 4X1X1/2" bars of mild steel. I would have them forge them into 2" wide bars, 8" long bars, and square bars. The first attempts were usually a dissaster. ... but once they learned to use the right heat, the right hammer, and the right tehnique, they came out pretty good. What they learned was drawing and upsetting. Those two forging techniques are all you need to master makig knives. Forge welding is a good additional skill.
Finally, practice, practice, practice! No one walks up to an anvil and forges a great blade the first time. A search on my first knife will show you how bad an inexperienced smith can make a knife look. Hopefully, I have improved a bit in the subsequent 57 years.
