Pattern pairing: Stripes and flowers mix for a low-key look

I have wanted to give pattern-on-pattern a try but haven't been sure where to start. So, I went to one of my fashion role models for guidance: My eldest sister.
Rather than give me advice, she decided to style my entire outfit ... and I have to admit ... this casual, weekend-friendly look she put together for me works pretty darn well.

                                                           How do you mix patterns?

Jacket, necklace and shirt (Forever 21), pants (The Gap,old), shoes (Tory Burch), bag (Marc Jacobs Stam)