I have never tried to set a bevel on sandpaper so I can't say anything about that, A DMT 1200 grit is great for bevels and is rather cheap, so is the naniwa 1K. Those both seem like they would be more consistent and easily to learn on then a piece of sandpaper.
If the heal is not hitting the hone while you're setting the bevel you need to put an ark in your stroke a little by leaning the edge (do not add excessive pressure!) towards the heal side of the razor. Then do some circle strokes while pushing that part of the edge.