Depends, for an object as basic as that, its not much you can do with it. It looks good like that, however, i suppose to make it more realistic, you could add a cut a few more faces around the top and bottom.

You could get some very realistic results by using a good texture and bump map. Or by adding cracks etc. but thats add more geometry, and if its for a game (which i dont kno too much about) you wanna keep your poly count to a minimum.

Not much help sorry