After years of folding paper dungeons I finally learned a few things the hard way, so here's what I wish someone had told me when I started making spooky tile sets.
Glue every fold twice. seriously, a thin coat on the tab, let it tack up for a minute, then press. Coffin mimics and tombstones get handled a lot mid-game and single-glue joints pop right open. I also trace my stone texture with a ballpoint pen before cutting anything, because trying to add it after assembly always looks flat. For graves that look sunken, cut a small notch in the tile where the prop sits instead of just gluing it on top. Cheap trick, huge difference. And spray your finished pieces with matte sealer from a bit of distance, close up it goes shiny and kills the paper look. Keep every piece on a standard grid footprint so you can rearrange the whole graveyard between sessions. I swap mausoleums, fences and coffins around freely now, one set gives me a dozen layouts.