This is the best author you've never heard of:
His name is Wallace Stegner. He's a Pulitzer Prize-winning novelist who's written such books as Angle of Repose, Crossing to Safety, and Big Rock Candy Mountain. He was a professor at Stanford for years and his students include Larry McMurtry (author of Lonesome Dove and co-screenwriter of Brokeback Mountain), Ken Kesey (One Flew Over the Cuckoo's Nest), Edward Abbey (The Monkeywrench Gang), and former Supreme Court Justice Sandra Day O'Connor. Ken Kesey once said learning to write under Wallace Stegner was like playing football under Vince Lombardi.
Stegner has a more robust vocabulary and greater command of the English language than anyone I've ever read, with Shakespeare as the one exception. I've stressed over and over than you should only be focusing on the annuals right now. But if you ignore that instruction and decide to read Big Rock Candy Mountain, you'll be forgiven.
But what I want you to remember about Wallace Stegner is this: Time and time again, he instructed his students that they must never think of themselves as writers. They must simply write.
You are not copywriters and art directors. You are not students. You are not fledgling advertising professionals.
Just go and make ads. Lots of them.