I think a good starting point is to think about what niche fairies occupy in your world.
Are they alien-seeming trickster types with orange-and-purple morality?
Are they personifications of nature? If so, do they represent both its nurturing and pitilessly destructive qualities in equal part, or do they lean toward one or the other?
Are they aristocratic hedonists who view humans as their own personal playthings?
Are they delightful beings who bring joy into an otherwise grey world?
Are they basically benevolent (though prone to anger if slighted) or basically malevolent (though capable of occasional kindness)? Are they beautiful? Scary? Are they tiny or human-sized? Do they steal children?
Fairies/fae have been and done all these things and more, and that's just in European folklore. I think if you figure out the core "vibe" of your fairies, you'll have an easier time choosing an appropriate visual form to convey the feeling you want.