Usage patterns
笑顔を見せるto show a smile
She showed a smile for the first time in a while.
笑顔で〈動詞〉to do something with a smile
He greeted us with a smile.
笑顔になるto break into a smile; to cheer up
Hearing the news, she broke into a smile.
笑顔がこぼれるfor a smile to break out naturally
Watching the child, a smile spread across my face before I knew it.
笑顔を作るto put on a smile (often forced)
I was actually sad, but I put on a smile for the photo.