The first rule of being an artist is you have to look. At everything! Whatever you're working on, look at examples, look at references, look at other things you might be able to incorporate in an interesting way.
Lately, I've been sewing. That means I look at people's clothes a lot. Probably too often, as there's always an available mass of them rushing by on bodies in droves. I keep thinking "oh, that girl probably thinks I'm staring at her, but I'm really just looking at the jacket."
I was just sketching this cute racer back tank that I saw on a girl in Chipotle a month or so ago. It was plain, light grey, but had a band of gathered material where the "straps" meet in the back. Such a cute detail! She probably bought it at forever 21 or some such, but it would be extremely easy to pull off at home. I'm going try adding this detail to a couple of things, as I build my home-made wardrobe. Which consists of nothing, at the moment. You have to start somewhere!