Ladies, ladies, you are all awesome! Apologies for my super late reply, had an intense work deadline to meet which knocked me offline for a while there >< This has been a FAScinating read; all of your responses are so insightful, you've definitely caught onto things I wouldn't have ever noticed (esp. Una, Steph, Suz, and Fruitful). While I don't pattern mix often I definitely feel that the information here is incredibly useful to keep in mind; this is especially true because I generally use analysis (engineer brain) when purchasing garments, but gut (artist brain) when styling outfits daily.
I do understand that pattern mixing is, itself, subjective so not everyone will like every mix (Una, I think my husband's eyeballs did explode at the sight of this one). I can also now see that beyond determining which prints "go" together (color, print, scale, style, etc.), there is a LOT more separate from the print that can affect the success of mix! Fabric, silhouette, and even hairstyle and accessories can serve to help or hinder the final outfit (though this is true with most outfits, I suppose). All very good food for thought.
The way this outfit came together: I wanted to wear this shirt, which is too short for pants. So I looked at my 3 summer skirts (the others being 1 white gauzy, 1 tan floral) and selected this one (for the pockets!). The print busyness called for nude/neutral accessories (silver earrings, metallic belt, nude+metallic sandals, gold purse). I didn't have a tangible reason for picking circular elements at the time, it just felt like that's what would "go" (but now I can see that it echoes part of the skirt's print). There was very little analysis that went into the individual item selection, it was all gut. But, you all know me, I like to understand WHY those gut decisions either work or don't