The first thing I would do is ditch the choker and replace it with something more elegant. It's not terrible but the bow in the front just looks bad. Maybe replace it with a pretty black lace choker that's a little smaller like this or a necklace like this or this. I feel like you should have an emphasis on the black but don't forget to use the lighter colors from the print as well and maybe keep a hold on the floral theme. I would go with Classic black shoes and then either black or ivory legwear. Maybe something with a little detail like these, these, or these. Since the sleeves are detachable and I personally think they're a bit much for is particular dress I like to suggest taking them off and maybe doing something else to get some detail on your arms like black wrist cuffs or gloves. Then you could bring those floral elements in with your jewelry and headwear with rings and corsages or a floral headdress.