We get asked about enclosures a lot. Important things to consider are space (as much as you can afford - sulcatas need A LOT, Russians, box turtles and other smaller species, not as much), visual barrier, constant access to clean fresh water, a secure place to hide underground or in a hide box or building, and lots of plants to eat and play in. Plant as much as you can. Use The Tortoise Table to figure out what you can plant, and see the Diet Tips page.
Note: These are NOT all CTTR's enclosures. Many are just photos that we pulled off the web to share.