Lauren Conrad has come a long way from her days as a fashion student and Teen Vogue intern on The Hills (which debuted in 2006).

Now the California beauty, who turns 26 on Wednesday, is a successful clothing designer (LC Lauren Conrad and Paper Crown), a New York Times bestselling author and the co-founder of the site The Beauty Department.

But the former reality star is best known for her impeccable signature look, which even inspired a book, Lauren Conrad Style.

PHOTOS: Lauren's 10 best hairstyles ever

Click through the gallery to see her best style secrets -- from updating classic pieces to mixing prints -- and learn how you can make them work for you.