Deserts are pretty easy. Narrow it down to what type of terrain you want.
Dunes? Soft sand? Hard pan? Rocky? Dry lake bed? Dry river bed? Oasis? Flat? Rough?
Then pick your scene. Like demono69 asked, what is the scene? What mind's eye photograph are you creating? what actual photograph are you reproducing? What is the scene? what are you trying to say?
Chhose a suitably sized piece of wood. Something stable, like a sealed plaque, piece of plywood, mdf, whatever.
Think about what you want to do and layout a quick sketch. I actually make cardboard cutouts so I have the "footprints" of the vehicles I'm using and I can check placement, scene movement etc.
Then from there you can lay down large or deep terrain features with foam or wood. Lay celuclay over that and sculpt the features you want. Add your ground material, sand, rocks, small plants and your tracks, roads, paths etc. When it drys, lay down your base coat of paint, then your wash and then your highlights. attach your subjects and away you go.
Now granted that is the Readers Digest condensed version but I think you get the idea. Think of it as a journey. YOu know where you want to go before you start and that makes the trip easier than if you just meander or wing it.
Mike
Mike
"Imagination is the dye that colors our lives"
Marcus Aurellius
A good friend will come and bail you out of jail...but, a true friend will be sitting next to you saying, "Damn...that was fun!"