By "unconventional" I mean things you don't normally think of. What things do you notice in other people that make you find them more attractive? Doesn't have to be sexual either; we gravitate toward people for many reasons and meaningful connections that aren't sexual are just as important as ones that are. I realize I placed this under "flirting" but that's just because I'm not sure where else to put it.
For example; for me, I notice the way a man's hands look. I also pick up on subtle mannerisms, choice of words, gait—and often these things stand out to me more than how conventionally attractive or fit they are.
I'm straight but I also notice things like this in women and find them attractive, albeit differently.