1. Flip them frequently during the day and cover with them plastic during the night. If they have started to warp, you can sometimes pat them flat with a paddle after they are too dry to bend.
2. Dry them on wire racks (like old refrigerator shelving) that have LOTS of air space under them.  Four inches of air space under each layer is minimum.  I have mounted some wire closet shelving in our ceramics room where it is high enough to be "out of the the way".
3. Sandwich them between dry sheets of gypsum board (drywall)(sheetrock).  This is paper covered plaster and it draws moisture from both surfaces.  Scrap drywall is available free from housing construction sites.  Cut one side with a utility knife and bend it to make pieces to fit your storage places. If you tape the edges with packaging tape or duct tape, you avoid the problem of plaster pieces getting into the clay rework. Be sure it is unpainted so it absorbs moisture.  These moist boards can be trashed or after complete drying they can be reused for another project. 

PROTECTING THE EDGES WHILE DRYING
None of the above solutions deal with the faster drying of edges.  I use one or more of the following methods to minimize this problem.  Small pieces may not need any special edge protection while drying.

1. Coat the edges with wax resist.  This is water soluble liquid wax used for decoration.  It becomes waterproof as it dries.
2. Leave scraps of clay slab butted tightly against all the outside edges. 
3. Place plastic sheeting tightly against the edges or plastic strips wrapped on the edges.
4. Double the clay thickness at the edges.  This can be done temporarily by laying strips of clay on the edges and removing them after drying is complete.

• Hint #2:  Firing Stacks of Greenware Plates
• Hint #3:  Setting the cone packs in the kiln.
• Hint #4:  Preventing Stuck Lids with Lid Wax
• Hint #5:  Preventing Warped & Cracked Tile 
• Hint #6:  Preventing Cracked Slab Boxes