Derided by some as a betrayal of her central character,the mod fashion designer Diana Prince Era of a depowered Wonder Woman might just be the perfect place to start her cinematic tale.
The basic story is this: The Amazons were loosing their powers and needed to relocate to another dimension to restore them. Rather than go with them, Diana decided to stay in "the world of men" without her powers.
So, she started a new life as somewhat normal person, opening up a mod fashion shop and training under the tutelage of I Ching to fight crime without her superpowers.
Make some updates and start her story here.
First I would fight the temptation to make her some super-rich fashion mogul. I like the idea of the most powerful woman in the world owning a modest shop where she can train and fight crime with anonymity.
Secondly, update I Ching (his name especially) to not only be mentor, but also a confidant and father figure the Amazons lack. She is content in her life of semi-retirement.
That is until Hippolyta shows up at her shop, informing her of the Amzons return, offering her daughter her powers back, and a return to her home. And a little pissed and hurt that Diana basically adopted a father.
Of course, she has to take up the mantle of Wonder Woman again, but I think she would initially refuse until something forces her hand (hint, father-like mentors being killed are a good place to start).
Her true origins can be related by flashback as she is confiding in her mentor.
One good reason to keep her at a fashion shop. You can update her costume more often than Captain America and there's an in-story explanation for it.
So, the most unpopular period of Wonder Woman's run could be a perfect place to start her in the cinematic universe.
Now, wait till you see what I have in store for Mr. Fixit Hulk!