I've seen a lot of people in jeans and basic tops at the theatre, but also other people were overdressed.
If you search this post's title on Google, you will see that this might be considered a major problem. It might sound funny, but people really need help when it comes to theatre outfits.
So, what should you wear? Of course you must be classy, but you don't have to wear gowns. And my other problem is black: stop wearing black, it's boring and only shy people wear it. Give colors a try!
*Wear a dress, but not a mini. These dresses are perfect!
(The first dress is a black one, I guess this is everybody's favorite, but please take a look at the other options, more colorful and vernal)
Pair them with elegant flats or heels (not to high!)
The other option: a skirt
Wear them with a shirt or a blouse, even a tee.
If you don't like skirts, ok, you can choose jeans. But at least wear them with a girly blouse, preferably a silk one.
Jewelery- few, small but nice and maybe shiny.
All jewelery items are from Swarovski
Bags from Asos
I hope this is useful!