Messing appears in Smash as Julia Houston, a songwriter and the co-writer of the show's musical based on Marilyn Monroe.
"Well, she's an artist with a capital 'A',' Messing told New York magazine. She's a mum, and very busy, but still creative. Her style is about being comfortable and practical.
"In New York, you never know what the weather's going to be, so layers are very practical. But I think she expresses her creativity in music and in the way she dresses. So many scarves and jewellery - that's the way she expresses herself.
"She's also a mum, so she's not going to be running around in tight pants and high heels."
An upcoming episode of Smash will feature Kill Bill actress Uma Thurman as Rebecca Duvall, who will be seen portraying Monroe on stage.
Smash airs on Mondays at 10pm ET on NBC, and it will premiere in the UK on April 21 on Sky Atlantic.
Watch a clip of Smash below: