Yeah, I guess it (and the other signs of the Zodiac) are proper nouns.
I will go as far past Genius on my own as I can, but then I look at SBB, first just the grids, then at the hints to see if there’s one that provides the first four letters and says there are more like it. After that, if it’s getting late and I’m really drawing a blank, I’ll look at the reader hints, but for me that verges on “cheating,” and I avoid it if I can.