Dead thread in a dead board but I'll play along.
In an RPG context, I am going to be traditional and go with Tolkien's interpretation. He's the one who synthesized all the old European legends together. His Elves are the Seelie and the Unseelie. They're the Álfar. They're the Elfen and the Druden. They're nymphs and satyrs and dryads and the Fay Folk. They're all of these mashed up, with most of the uglier bits of their legends trimmed away, to make them beautiful shining inhuman creatures out of legend, not quite Gods, more beautiful and perfect than humanity.
And I think I prefer them as he wrote them, as his writings were so influential on RPGs. As such, they fall into two general groups, more or less. There are the High Elves who wear elaborate formal dress, and there are the Wood Elves who wear dull dark earth tones, the better to hunt. High Elves have very fancy armor and weapons when they go to war, and I suppose they have very practical clothing, presumably of very high quality, available for when they go dungeon-crawling. See second image.
If we're talking about sci-fi Elves, and I am not sure that juxtaposition goes together well, for all that Warhamster40k is so popular in nerd circles, then I will go with what the writers say about the influences. The Eldar are Europe's pagan past, with electric wraithbone swords in the shape of a xiphos and tall Corinthian helmets made out of magical bulletproof unobtainium. And like the pre-Christian pagans, they are doomed, doomed, doomed. All their neighbors are pushing them back, taking away what was theirs, forcing them to accept alien ways that change them utterly and make their children strangers. They are dying out--but they've got one last good fight left in them.
I will also say that, in general appearance, I like Poul Anderson's interpretation of Elves in "The Broken Sword." They are humanoid but not human, with rather less sexual dimorphism than humans, and an eerie androgynous beauty and an alien aspect that extends rather beyond just pointy ears. The androgyny extends to behavior. It was alluded to rather bluntly, for a novel written in the 1950s, that male Elves are generally smirking low-T types generally lacking much in the way of a libido, though they are cunning and quick to anger, and that Elf women are quite a bit hornier than human females and not averse to yoinking teenage human males who strike their fancy off into the bushes for a bit of the ol' ara-ara~. Elf males are charismatic, every bit as xenophilic as we are, and have a tendency to seduce young human women by the dozen and leave half-Elf babbies all across the countryside, though they are not normally born with anything as obvious as pointy ears. Both sexes among the Elves seem to be more interested, sexually speaking, in humans than in other Elves. It's probably why they're going extinct.
And if we're talking about other than the /tg/ context, Elves should only be girls, and they should wear fetish gear, because Elf chicks are sexyfine. There, I said it.