How Do You Do Casual?

I usually wear a dress every day but sometimes I feel like looking a little sporty, a little tomboy, with a twist, of course. The problem is, I'm terrible at it. I'm not a big fan of jeans. I have a legging pair and some black skinnies. I don't feel like heels: My feet hurt and I'm tired but I still want to look cute. I actually try to not wear a dress some days. Usually I end up just looking weird. Last weekend, I worked Saturday and it's casual so I wore black Lululemon pants, gold glitter sneakers, a Saved by the Bell tee, puffy shoulder cardi, and a headband with a bow. SO random. Oh, and glasses. I want to look more effortless. And chic. My 1950s curves don't really work with tomboy clothes but girls like Scarlett do it so well so I should be able to. Any ideas? What do you wear on casual days?