At the world premiere of "Country Strong" on Monday night in Nashville, Tenn., Paltrow said it was important to get her character right.
"I think any time you do any role you want to be as authentic as possible, but obviously in this case with it being around the world of country music, you have a whole culture to really respect and portray properly. So, it was some pressure," she said.
To prepare for the role of troubled country star Kelly Canter, Paltrow watched a lot of concert DVDs and YouTube clips of country stars. She said she relied on advice from girlfriends who are singers more than from husband Chris Martin, lead singer of Coldplay.
"It was a lot of work, but it was really fun. It was worth it, very challenging," she said.
Paltrow plays a singer fresh out of rehab who's trying to pull her life, her career and her marriage together. Tim McGraw plays her manager/husband, who seems to be more interested in fixing her career than their marriage. McGraw says the key to keeping a marriage healthy is to support each other.
"I'm always her biggest fan," said McGraw of his real life wife, Faith Hill, who also attended the premiere with him. "I think that we totally support each other. I think that's what a marriage is about, supporting each other in whatever you do, and whatever your goals and your dreams and your aspirations are. I think that's what it's all about."
Leighton Meester plays pageant queen-turned-country star character Chiles Stanton. She said it was easy to relate to her character, who looks up to McGraw and Paltrow.
"Tim McGraw, he's so funny and so cool and really just awesome, and of course, he really knows the ins and outs of the business," said Meester. "He showed me the ropes, told me what it was all about and really was like a mentor on and off screen. Gwyneth, of course, you rise to the occasion, and she's so talented and gorgeous and effortless. It was really, really a joy."
Meester filmed the movie while her TV show, "Gossip Girl," was also in production. She said she would fly to Nashville on weekends, shoot, and then go back to New York.
"I fought for this role," she said. "The character is so different from anything I've done. She's so well written, has such a heart, very flawed, but really cool, and of course the music and performing aspect of it was a challenge as well, but it was really great."
McGraw was happy that most of the film was shot in Nashville. That meant he could sleep in his own bed every night.
"It's fantastic. Nashville's a great town. We love this town. We love everything about it. We love the people here. We think it's a great place to shoot movies, especially if we're in them so we can stay home," he said.
Hill quickly added, "But not too many."
McGraw laughed, knowingly: "Not too many. We don't want to overdo it."
"Country Strong" opens nationwide on Jan. 7.