My latest method is to use plastic clothes hangers, but specifically the ones with the two plastic clips. Simply clip to two corners of the prints (I usually clip on the smaller dimension), then clip two clothes pins to the two lower corners for weight.

This gets the prints reasonably flat, enough for inspection and/or storage. After that, I dry mount.

In my experience, fiber prints need to dry for 2-3 days, at least the Ilford papers that I use. I expose and develop so that the brightest highlights are without detail. After a day, I think I've screwed up, but somewhere in the second day, those highlights begin to pop out. Getting control of this has made a huge difference in my printing. Try it; it takes patience, but is well worth it.