Forging is a huge chunk of the reason I love bladesmithing so much. The clanging of your forging as you smash the red-hot steel with your hammer, forming it into a beautiful cutting weapon. What's not to love about forging? It's exciting, it's just the right amount of danger, it's exercise and it's calming. It's a stress release. A bladesmith even started a program teaching veterans how to make knives for this purpose.
Apart from this, especially as a bladesmith lacks the tools to get grinding done quickly, it's faster to shape the blade through forging rather than completely grinding; especially if you're using a file. So, how is it done? First, some basics in forging.
Forging takes some practice. Start out hitting too hard, and you'll make a mis-strike and make an unfixable deep mark in the steel. As you get more comfortable, and gain muscle memory, you can increase your striking power and so go faster.
First of all, make sure the tongs and secure; that there's no wiggling, even if you ease up pressure a bit. Not only does it decrease risk, but makes the forging much cleaner and easier to control. Make sure the anvil is at the ideal height (if you stand up straight with your arms at your sides and hammer perpendicular to your arms, the face of the hammer should be level with the face of the anvil). If you're trying to thin and lengthen the steel out, make sure to flip it 90 degrees every so often so you don't pinch the steel in on itself. Work slowly and carefully, and stop forging when it begins to turn black. Start out with a heavier hammer for the bulk of the work, and switch to a lighter ball peen for cleaning it up and forging in details.
A principle, simple and intuitive, to keep in mind, is when you strike flat with the hammer, kinetic energy, and the steel with it, is sent evenly in every direction in two dimensions. If you had a cube, red hot, and hit it with the hammer, it would be squished down. The steel has to go somewhere, so it goes out the sides, evenly. If area decreases in the Z axis, it increases evenly in both X and Y. If you want to turn the cube into a rod, hammer down with the Z axis facing up, then the X axis, then Z and repeat. Each time you strike, the steel expands in the X direction (as well as in the third direction you are not hammering, but that gets nullified when you flip it on the other side), never getting hammered back to where it was to begin with. If steel is moved, it must go somewhere.
With all that under way, here's my personal process.
Forging steps: the Tip
Start with your steel. I'll assume the steel is a file or rasp, or a similar shape. Make sure there is a good deal more mass in the steel than you guess the final product will be, both because of forging complications and the loss of material through oxidation.
If you have the means, cut off the tip of the bar at a 45 degree angle. If not, you'll have to forge the angle in: heat up the tip of the blade, and do some steady strikes on the corner, at a 45 degree angle. Don't hit too much from the top; as this can pinch the steel in on itself, making a crack in the finished product. Tap on the end every once in a while, and flip and hammer on the flat (wider) side only when it starts to pinch. Once the angle is forged or cut in, it goes back into the forge.
Heat up the last couple inches and start gently forging it down, making it less steep and more tapering of an angle. The more you taper it now, the more it'll end up being tapered as a finished piece. Flip it on its side every once in a while and flatten it a bit.
Now, keep in mind the sloped and tapered side will not be the cutting edge; instead, it will be the opposite side. This is because when you forge the bevels in later, the steel expands to the side, curving the blade backwards, and the tip up. Having it curve down now keeps it from curving up later.
Forging in the heel
The heel is the end of the cutting edge opposite the tip. You'll start forging it in first, at about the distance from the tip as you plan it to be in your design. Place the hot steel on the anvil in front of you, side up and at a slight angle, resting the future heel on the corner of the anvil. The edge towards you will be the cutting edge, so make sure the taper looks like it's curving towards you. Start forging, with the hammer at a slight angle to bevel it, and hammer in "pulling" motions, which forms the steel more towards you rather than out to the side. This should curve the steel sharply backwards at a shallow angle. Keep forging, reheating as necessary, until the future cutting edge is about an eighth of an inch thick, maybe a little less. If you're careful and hold the piece steady, you'll get a sharp "pinch" coming out of the bar. Even out this pinch by forging lightly on both sides on the pinch itself, centering it.
Curving forward and flattening out.
Place the bar on edge on the anvil, the heel facing down over the corner of the anvil, and start lightly tapping near the tip, curving it forward. The goal here is to make the spine of the knife straight with the rest of the bar, instead of curved back, and to start curving the whole blade forward. Remember at this point it's even thickness, except for at the heel, and curving it forward compensates for when we bevel it. Don't curve it forward too much, just enough to be clearly noticeable. If you don't do it enough now you can do some more during beveling. Put it on the flat and even and straighten it out, knocking out any pinching that formed. Start forging towards the tip, to taper it into a point.
The blade should be flat on the anvil, tip heated up and edge towards you. Do a few gentle but firm strikes at the tip, angling the hammer slightly to bevel it. Make a pulling motion as you go, as if your elbow is going in a circle. This "pulls" the steel more towards you, and less towards your let and right. Do clean, overlapping strikes. Remember; any deep marks you make now, you'll have to fix now; they are extremely hard to grind out later on. Work towards the heel, straightening and flipping over every now and then to even it out. If it starts to curve back too much, heat the section that curved most, place the bar (before it gets to the heel) on the anvil and tap on the tip, curving it back forward. If this doesn't work, you can place the blade edge down on the anvil wait for a few seconds for the edge to get black; the anvil acts as a heat sink. This way, you can forge and straighten it without deforming the edge too much.
As you finish up this, start forging it closer to your design; remember you want it to be bigger than the drawing, not smaller. If it's too big in some areas you can grind it out. If the blade needs to be narrower at certain points, hammer equally on the two axes, switching back and forth; this will both narrow and lengthen it. Even it up and refine the shape, switching to a lighter hammer to smooth it out and work in the details, especially the tip. Forge carefully around the heel, so you don't go past it and start hitting the ricasso; the point between the heel and the handle.
Ricasso and Tang
Cut the tang off the rest of the bar at an angle, about a hand-width behind the heel. Put the tang on the anvil, blade hanging over the edge of the anvil, with the anvil corner about a centimeter away from the heel. Blade edge pointing down. Start hammering, pinching this in. This pinch will form the point where the ricasso ends and the tang begins. It doesn't have to be much; an eight of an inch will do. Start forging down the rest of the length of the tang, tapering it into a point. Flatten out any pinching or uneven surfaces, and even out with the lighter hammer.
Finish matching up to your design as close as possible, evening out the bevels, flattening the ricasso, tapering the point and tang, and above all, straightening the blade. Look down its length from tang to tip. Make it perfectly straight. Any flaws, clean them up now.
As the blade is put under a lot of heat and stress, the atoms form large "grains"; visible if you broke the blade. Steel of large grain size is very brittle, and breaks easily. The goal of normalizing is to make these grains smaller, which increases the number of bonds and so the strength of the steel. This is done by heating the entire blade evenly in the forge to a little above "Critical Temperature": the point at which a magnet will no longer stick to the blade. Heat it up, then take out the blade and let it air cool until it's completely lost any color, then repeat twice, for a total of three times, the last letting the blade air cool until room temperature. Then, it's on to grinding.
Forging takes a bit of practice to do. Your first blade will not be all that good, but stick to it. Put your mind to it, and your skill will advance and a shocking rate. Go slow, take it easy, have fun. Steel is tricky to get it to go where you want it to. Get used to it, and you'll know what it will do in any situation.
Note: This is a very good tutorial by Kevin Cashen, showing the forging of a blade. Due to copyright, I was unable to use the photos, which no doubt you will find priceless.