I never use anything specific but I do use some kind of bookmark, whatever's closest to where I'm sitting when I'm reading. I always look at the page I'm at before I put the bookmark in there, but I always do use a bookmark. When I was much younger I'd fold the corner of the page and use that as a bookmark. xD Never liked it cause I don't like ruining books like that, but I was lazy like that at times. >:D I stopped doing that years ago though~

As a side note I'd like to add that, by far, I much prefer reading actual books than reading them digitally, and I always will. <3