With designers and stylists on speed dial, it often feels like celebrities have the cheat codes for looking good. But that isn’t exactly the case for Isabelle McNally, the up-and-coming actress who plays Madeleine Loomis on Bates Motel. She prefers to do her clothes scouting and shopping on her own, and she does it all online.

NEW YORK, NY - APRIL 18: Actress Isabelle McNally attends the "Loitering With Intent" Premiere during the 2014 Tribeca Film Festival at BMCC Tribeca PAC on April 18, 2014 in New York City. (Photo by Neilson Barnard/Getty Images for the 2014 Tribeca Film Festival)

“I’ve always had an aversion to dressing rooms — they’re often so poorly lit,” McNally told Vogue. “My dedication to online shopping began five years ago.” But knowing how things bought online will actually fit is often the most daunting task. Therefore, McNally has a hell of a trick to make sure what you see is what you get.

“Know your measurements,” she said. “Get familiar with the silhouettes that flatter you and how they look when they’re flat on the ground or on a hanger.” Most online retailers include measurements for clothing, so knowing exactly what size you are will definitely help you know how a piece will hang on your body.

If you don’t know your measurements, you can either pop in at your tailor’s and ask for ’em, or there are several tutorials online, including this one from Lauren Conrad’s lifestyle site, that teach you how to do it yourself.

NEW YORK, NY - JANUARY 14: Actress Isabelle McNally attends "Loitering With Intent" New York Screening at SVA Theater on January 14, 2015 in New York City. (Photo by Dimitrios Kambouris/Getty Images)

As for where McNally is spending all of her time online shopping, she likes The Line (a good place to start as a beginner who doesn’t want to dig), Yoox (for intermediate shoppers), and Japanese marketplace Rakuten (for super duper experts).

Happy shopping!

Now, who has a measuring tape? Let’s put her advice to the test. Tweet us @BritandCo.

(h/t Vogue; photo via Isabelle McNally, Neilson Barnard, Dimitrios Kambouris/Getty)