AThere was a young woman who was wearing a green apron over a red shirt. There was a young woman who was wearing a green apron over a red shirt.

The narrative flows a lot better with the additional words. On the other hand... if I am imagining the scene right, I think the green top the young lady was wearing would be a camisole and not an apron. (An apron is more usually worn for kitchen-related tasks.)

A young woman was wearing a green apron over a red shirt. A young woman was wearing a green apron over a red shirt.

It's not clear if this woman is a Starbucks worker or another customer. I guess it doesn't matter, but you could add some words to make it clear. For example, "A young woman behind the counter was ..." "A young woman in line was ..."

A young woman was wearing a green apron over aher red shirt. A young woman was wearing a green apron over her red shirt.

I thought that she was clearly goingdressed for a Christmas look. I thought that she was dressed for Christmas.

So I joked, “Are you wearing the uniform of Portugal’s soccer team uniform today?” So I joked, “Are you wearing Portugal’s soccer team uniform today?”

She smiled and said, “It’s for Christmas,” then turned around to show me the word “Christmas” written on ther back. She smiled and said, “It’s for Christmas,” then turned around to show me the word “Christmas” written on the back.