Forging a double edge blade is a little different than a single edge. I begin by forging the profile of the blade starting with the point. You will want to make the profile slightly undersize and you will have to work with it until you discover how much the edge is going to grow as you forge the bevels. It is important to keep the blade stock flat and slightly thicker than the finished dimension. Once it is flat, keep away from it with the hammer.
After the blade is profiled, you begin shaping the bevels. Remember to set the angle of the anvil side of the blade by tipping the bar toward its edge. Beginning at the tip, start to forge from the edge back. I usually work one edge at a time and try to give an equal number of blows on both sides of the blade. I do not forge to the centerline, but merely start the bevels along the edge. Watch your work and if you find that you have a great bevel established on one side, but it is flat on the other, you are not tipping the blade enough on the anvil. Remember it is making an impression from the anvil side as well as the hammer side. Be sure to keep the blade parallel to the face of the anvil or it will start to bow on you. The hammer hand is the power, the tong hand is the brains. Keep your elbows in and locked to your side, striking the anvil in the same place and moving the stock by rotating your hips. This may seem awkward at first, but it minimizes the variables that come into play with a flapping elbow.
You should be working heats just above critical, dropping them as the blade approaches finished dimensions. The second heat, work the other edge being careful to keep the shape and curve similar to the edge you just forged. Work this way the length of the blade until just before what will become the ricasso area and the termination of the bevels. I like to set my bevels at this point by moving to a sharper edge on my anvil and carefully marking the stopping place by beating it in at this point. Then I finish forging to the mark being careful not to let a random hammer blow mar the ricasso area. Your blade should now have the beginning bevels established on all planes of the blade and it is time to go back to the tip again and begin working up the bevels. The process is the same, but this time you can work to finished forging. Stay off the center of the blade. If the blade must be trued use a rawhide or wooden mallet on the anvil stump or another piece of wood so you don't put a ding in the flats.
Sight down your work often during the forging. There is a tendency for the blade to want to corkscrew and if you catch it early enough it is easy to get out. I try to straighten the blade at the end of each heat so that when it comes out of the fire for the next heat I am working off a true surface. If you see a problem, it will always be a problem, fix it when you see it. Once the blade is nearly finished, reverse your hold and forge in the tang.
I recommend cycling the blade to critical and down to black heat at least three times after all the forging has been done. This will refine the grain and reduce the stresses in the blade. I do not anneal my blades, but do all work from a normalized condition.