When it comes to fashion, Pamela Skaist-Levy and Gela Nash-Taylor can be summed up in one word: unstoppable. Starting with their first line, Travis Jeans, in 1988, this California-based fashion duo has gone on to launch three more brands, including the worldwide Juicy Couture phenom and its iconic velour tracksuit craze (just ask fans like Madonna and Paris Hilton).

The best friends eventually sold their company to Liz Claiborne in 2003, where they stayed on until 2009. In 2012, they announced the short-lived Skaist-Taylor line, followed by this year’s debut of Pam and Gela.

LISTEN: Toms Founder Blake Mycoskie's Summer Playlist

Now, with four lines and more than 25 years of experience in the fashion world under their belts, these style-savvy entrepreneurs have packed their best business lessons and advice into the newly released The Glitter Plan: How We Started Juicy Couture for $200 and Turned It Into a Global Brand -- the ultimate how-to for anyone looking to create the next great American fashion brand, or seeking a deeper insight into the inner workings of the industry.

And if a how-to bible isn’t enough to get you motivated to build your own fashion empire, check out the duo’s juicy playlists below.

From left: Pamela Skaist-Levy's playlist and Gela Nash-Taylor's playlist