http://www.scale-models.co.uk/threads/some-old-warhammer-dioramas-sadly-they-be-gone.19221/ This link shows some old warhammer playboards I made for my lad. I make a lot of dios and the first thing to make is the base for the model scale that is intended, too small it will looked cramp, too big it will look lost, next is to get an idea of what bits and pieces you need to put on it.
Desert one is easy: A base. A area for the aircraft to sit on, fake concrete setting or the like. A desert setting surrounding the runway, this can be achieved by using sandpaper, sprayed desert colour then various sponges added, or, this what I do, I build it up using real sand-use PVA to attach, once dry, add more PVA nd more sand to build up areas, spray when done and sponge. Add some rocks and grass clumps.
May give you some ideas Will.
Si