Whether you are teaching at home or in a school, large picture cards can be a great help. To be honest these days I usually use the software section of the Genki English CDs and a projector.
But if you don't have a projector the A4 picture cards you'll see linked
on each theme's page are very useful.
You can of course re-size them and print them out at any size, A3, B5 even
A1 poster size.