"Mostly whether things were getting squashed in the wrong way," she said. "You know you're going to have good lighting and positioning to help your body out."
The 39-year-old "Blue Bloods" star, who has a 3-year-old son with ex-boyfriend Tom Brady, said she usually prefers to be in her birthday suit only "in the privacy of my own home."
"In this electronic age, it's not safe to be naked anywhere else, even in locker rooms," she said.
But the professionalism that comes with a magazine shoot made stripping down a worthwhile experience.
"I've been in the business a long time, so it didn't really faze me," she said. "I was completely comfortable."
"I've always wanted to be sure my parents approve of what I do," she told the mag. "Even with my tattoos, my mom went with me. The 'believe' tattoo is because my mom always told me to believe."
With six workouts a week, the "Hellcats" actress had an awfully fit physique to show off, but Tisdale actually had additional motivation.
"I'm 25, almost 26, but people think of me as much younger because I look young," she said. "Being in this shoot was me saying, 'I'm not just the young girl everybody thinks I am. I'm actually a woman.'"
The mag's annual nude issue, on sale April 19, features two additional beauties in the buff: musician Keri Hilson and "The Big Bang Theory" actress Kaley Cuoco.
Past participants have included comedienne Chelsea Handler, "Entourage" star Emmanuelle Chriqui and former "American Idol" judge Kara DioGuardi. (Source)