I use crisco if the fondant has tiny fractures. But if it looks good and you just want shine you have a few options. For dark colors all you have to do is take a paintbrush with a drop of water and paint the fondant with the damp brush. The dark colors get shiney.
For light colors you can try the same, but they won't glisten as well. Depends on the type of shine you want. Pearl or luster dust gives a great shine, but it's a different type of shine.
Steaming does the same thing, but the shine doesn't last as long.