I flat grind most of the way first, down to 0.03" or 0.04" at the edge depending.
I put two layers of tape where I don't want to remove material (ricasso, high up the bevel etc).
I use 120 grit, with lots of tension, but on a slack unsupported spot above my flat platen, where the belt is running horizontal. I stand to the side and have the edge away from the incoming belt. Equivalent to edge down. You need to be careful how you hold and move the blade. Further away from the platen is less firm. Drawing it close to your platen will be firmer and steeper. You can easily create a very thin edge and overheat. You need to be especially careful getting the angles you want near the tip.