I'd really recommend staying away from loose substrates, including sand, cocofiber, reptibark, etc. For the geckos I have in tanks, I use tile. I found slate tile at Home Depot that came in small squares so I sort of have a cobblestone look. I have two identical hides - one one the warm side and one on the cool side. The hides shouldn't be too big - just big enough for the gecko to squeeze in and feel secure. In the middle I have a homemade humid hide. Then there's a water bowl and a food dish with calcium w/o D3 in it (and sometimes also some sort of little dish for the calcium instead). I create a heat gradient using an UTH hooked up to a thermostat, and have a thermometer with the probe under the warm hide. I like to have some sort of background for decoration.

Here's a picture of Pip's tank, a 20 long:


Here's Godzilla's tank (for now.. it's a 10 and I'm going to move him up to a 20L once I get some more tile):