Answer:
Branches, rocks, a water dish, hides, basking spots.
Do not put in: calci-sand or any kind of sand, the last thing you want to do is encourage the lizard to eat sand, you want to make sure it eats as little sand as possible because it can cause impaction. Deep water dishes, these can cause extra humidity and cause lung problems, also the lizard could drown itself. Also make sure your branches don't have any pointed ends, and if you get branches from outside make sure you disinfect them properly.
Agree 98% with answer above, however the Dragons natural substrate is sand. While it is very true sand can cause impaction, there are certain sand blends that are extremely fine (more like desert sand, less like beach sand) and therefore greatly decreases impaction risks. There is also ground walnut shell that retains heat well and other non-granule substrates. Your main goal is to have it be something that if digested (and it will be when your dragon eats live pray) that it will pass easily, I believe that is also what the previous commenter was meaning.