It might sound strange but I used to be able to *almost* WILD (not that I'd even heard of lucid dreaming, or would have known what I was doing) when I was a lot younger. One thing I did notice was that I would often wake up with a very strong afterimage that I couldn't get rid of easily for quite a long time after I woke up. As far as I know it wasn't induced by an afterimage technique but I remember it always being an image of a thick circle (like a slice of pineapple&#33 which would pulse from yellow to purple depending how hard I tried to get rid of it. Maybe this was somehow related? Sounds like a good technique anyway.