Plain small gravel is fine. You can use coconut shell, or 3-4 inch clay pots (I soak mine to make them soft and then take pliers and break of a bit for an entrance, and put them big end into the gravel.) Plants are good, you could have Java moss, java fern, anubias...anything low light, unless you have a lot of light.
They prefer (from what I have read) soft, acidic water. I keep my temp at 78 F.
HTH