Spring toggles are another good way to fasten to a hollow wall, such as plasterboard as long as the plasterboard is fastened to a stud partition. If the plasterboard is bonded to a brick wall there may not be enough room for the spring toggle to spring open.
Here I have made a hole in the plasterboard with a screwdriver (you don't need a drill for plasterboard). This is just big enough for the spring toggle to pass through.
Once the toggle is in the closed position like this it will be small enough to pass through the hole.
I have placed a penny washer on the screw of this spring toggle to prevent the head from dropping through the hole.
Here on the reverse of the board you can see that the wings have sprung open and distribute any pull out force over quite a large area.
One disadvantage of the spring toggle is that if the screw is removed from the hole for any reason the back of the spring toggle will drop off and could be lost. For this reason there are much better alternatives that will leave a threaded hole in the plasterboard!