...which includes me is to do everything that Wiley says, but grind facets off in the curve (as wiley says, always grind the iron edge at 90 degrees and then restore the bevel. The work will be much safer and faster) until you have a near curve, and then the curved work will be easy.
I no longer draw lines, but do the facets (but I have done a lot of irons, so that's not a suggestion for a first). It's just easier to see than judging a curve. If the facets are even, when you knock the points off to make the thing a continuous curve, you'll have a nice smooth curve.
This is good practice for a lot more than irons, but I'm sure the first place I ever saw it was a handle-making tutorial from Mike Wenzloff. It's invaluable in that case.
I have an iron that I need to grind to a curve and can illustrate or take a video if it's helpful.