Glue the prop to the stage with the hot glue gun--if the prop is not made out of wood, luan or masonite. Apply glue to the prop and then quickly place the prop onto the desired part of the stage or scenery until the glue solidifies the hold on both the prop and its new base.
Drill a hole through the base of a prop made of wood. Drill a screw through the hole into the object you wish to attach the prop to--the pre-drilled hole prevents the wood from splintering from the outward pressure exerted by the motion of the screw penetrating the wood.
Staple hook-and-loop fastener to the bottom of a prop--using fabric staples-- and attach another piece of hook-and-loop fastener to the table or other surface where the prop will be placed.
Attach a table or chair to the stage with screws. Drill holes diagonally into the stage below the chair or table, about 1 inch from the stage surface on each side of the leg of the table or chair. Drill a screw through each hole--this should secure the prop to the ground. Drill the holes and screws into the upstage side of the legs if you wish to disguise the screws.