I know it's crazy for me to be wearing a jacket in summer, but they keep the air conditioning in the dance studio cranked way down. (Or up, or whatever. It's super cold, is what I mean.) I wore a sports bra and shorts to my first class, and I regretted it so so much. So now I wear leggings and a jacket I can take off if necessary.
Also, yeah, mostly older ladies in my class. I'm not sure they approved of what I wore to my first class.