Find a name that's catchy and rolls off the tongue easily. An unduly complicated name will be difficult to remember and tough to pronounce. Superhero names should be as memorable as you can make them, which means short and compelling. Think of it as a form of advertising or branding, only instead of soap, you're selling a character.
Choose a name that reflects the hero's powers or overall theme in some way. A hero with powers of cold generation, for example, should not be named the Fiery Inferno. The name should also reflect a certain sense of grandeur, reflecting the epic nature of many superhero comics. Think bigger, more astonishing and with a larger-than-life feel. It's almost impossible to overdo it as far as superhero names go.
Come up with a subtitle along with your hero's formal name: something to go under the header on the comic book cover. Superman is the Man of Steel, for example. Batman is The Dark Knight, and Spider-Man isn't just Spider-Man, he's The Amazing Spider-Man. A subtitle should follow the same rules as the formal name--it should be epic, enticing and give the reader some idea of what the hero is all about.
Stay away from simply sticking "-man" or "-woman" at the end of a descriptor. In the first place, all the good ones have been taken. In the second place, it lends itself unduly to mockery and parody. If you're shooting for a campy or satirical superhero name, it may be appropriate. Otherwise, find a more original means of expressing who your superhero is.
Consider whether your hero will incorporate his name into his costume. Superman, for example, has a big "S" on his chest (though in canonical terms, the "S" is coincidental) while Spider-Man and Batman both have images of their trademark animals on their suits. Not every superhero has to incorporate his name into the outfit, but if yours does, make sure the name fits it appropriately.