One can carve steel with regular gravers, and a chasing hammer. regular engraving tools will do, you can get some from Brownells, or Ngraver supply company.
You can do large carving on steel with cold chisels, but it may be hard to get very fine detail that way.
You can do a lot with needle and riffler files also. really small stuff can be filed with what are known as escapement files, which are very small needle files designed for watch and clock work. Companies like Rio Grande, who sells jeweery tools, will have such things.
You can practice on wood first, esp the filing. Engraving and wood carving are not exactly the same, but most of the techniques overlap.
here is a link to a tutorial which may help. Not my work, but very helpful stuff.
metal carving tutorial
HTH, and feel free to ask any more questions, and I'll try to help.
Tom