The blue dress is not the most flattering shape for you, BUT I love the color, so let's work with that.

You said it can fold down to be a flowy skirt.  I would pair it with a white tank top like this by Splendid



And then layer on jewelry.  It's pretty predictable to do a big statement necklace, so I would go for a couple simple strands and then perhaps layer on bracelets.

This necklace is from Forever21:



And so are these bracelets.  I like the idea of a cuff or something and maybe a couple of slim bangles on one arm, with a pile of bangles on the other.



(For that second set I'd probably eliminate the bottom, rhinestoned out bangle, but that's a matter of preference )

Then, because you want to be laidback and flowy, I'd finish it off with flat sandals.  The obvious choice are your standard flippies from Old Navy, but something a bit more delicate is far more interesting and makes the outfit more of a choice than an unfinished idea.  These are from Nordstrom and are by DV by Dolce Vita.