That sounds awesome! I can't speak much to fashion as it's something that always sort of escaped me a bit. I think general would be the way to go at the start since the site is small and you can make a second more specific sub later. You could enforce rules and general guidelines about not body shaming people. I'm afraid I can't offer tons of advice as I'm not much into fashion but I encourage you to make the sub! Just try and post lots and try to draw some more people. To discourage hug boxes you could also put a guideline perhaps for posters to be more open to constructive criticism so long as it is constructive. Maybe you could use flairs to separate people who are looking for constructive criticism and those looking just to share their fashion. Hopefully I was of some help :)