I'm 26, bi, and I usually have to state my sexuality as a clarification when a girl says "so, I know you're gay, but..." But I don't really 'dress gay' (at least not with this expressive purpose). For the record, I also do the tall-thin-skinny-monochrome look. Some points of advice:
Don't sweat it, as u/plo83 says. If you 'dress for your sexuality' and are not comfortable in it, it will not do anything for you. If you stand in front of the mirror every morning and can say to yourself "I look great" then you're golden. In short, don't be a cliche for the sake of being a cliche.
The 'gayness' is (in my experience) more body language than dress. We all went to that phase where we did 'gay hand movements' until our joints hurt, but that's really not the answer. It will come naturally. It has been pointed out to me (by a gay friend) that the way I cross my legs is a 100% tell. Whatever.
Gay men are not into girls, otherwise they'd go for girls. The 'feminine' of girls and the 'feminine' of gay fashion are noticeably different. I wouldn't take too much cues from women's fashion. On the other side, androgynous pieces are excellent.
Statement pieces. It is a stereotype that gay men are more fashionable than straight ones, and you can make that work for you. If you wear something that is obviously a 'fashon piece' (so not something anyone can just pick from a rack at H&M or Zara) then you are read as less straight. So basically, I pick the pieces from my wardrobe that one does not buy unless one explicitly searches for them.
When I'm out with a girl, I tone it down. Slightly looser pants, a decent (t-)shirt, jacket and nice but not flashy shoes. You want to look slightly above the stuff that any man who is semi-concerned with their appearance could buy if they would go into any large-ish store. For monochrome this means that you want something in a definitely nice cut, but not the asymmetric/drapey tops. Think Lemaire, not Rick Owens. Girls are sometimes intimidated by too fashionable men, and everyone is intimidated by bisexual people (they always assume you are going to leave them for the other side; you'll learn that the hard way), so you don't want to send confusing signals. Unless the girl is really into fashion, then go all out.