Don’t trust anyone who claims they “know” fashion. It suggests they’ve reached some kind of finish line, an absolute state of enlightenment. It is impossible for a person to know everything about fashion. Whatever you think you know today could change tomorrow. Fashion moves quickly.
Don’t let Tumblr bloggers trick you into thinking that “knowing” fashion and being a pretentious fashion dickhead is cool. It’s just like any other interest you cultivate. There is no secret to it.
It’s okay to reblog a grainy 90s detail shot of archival Yohji Yamamoto just for the hell of it. Nobody is going to quiz you on it.
"Amanda Murphy in Prada fall-winter 2014 shearling coat, photographed by Steven Meisel for Vogue Italia August 2014" does not mean that someone "knows" fashion.
If you’re genuinely interested in learning more, write a blog. One of the best ways to learn is to teach somebody else.
Marc Jacobs once said that his creative process starts off with a blank piece of paper, then he draws a dot in the centre, then works around it. Start small, and let that interest grow organically. Whose work do you really admire? Study it. Read reviews, explore their references, and think about who they’re dressing. You’d be surprised how quickly you can get that ball rolling.
You don’t have to take a class to “know” fashion. There isn’t an entrance exam.