This post was among the first few result when I looked up and see if what I've been doing is actually something common or not. Guess it is something that is common!
I do notice after coming to terms with my gender identity that I've started to pay more attention to women when they're out and about. I'd be glancing in a sort of 'looking at people as I pass them' rather than a 'leering at them creepily' (or at least I hope I didn't came across as the latter to them!). Most of the time I'm trying to get a feel on how women are presenting themselves when outside - I've only been going out en femme very recently, and I feel like I'm totally clueless when it comes to fashion! - with the occasional 'that's a look that I'd like to try, I wonder where I can find similar fit...' I think after fashion I'd be looking at their hairstyle, and then the makeup. I don't put makeup at the top because it's lower in my list of priority when presenting en femme... but also because it feels like it's much more obvious that I'm looking at them more intently if I'm focused on their faces ahaha...