I think that's really cute! LMonet's idea of tights is good - they might make it look less fancy and more funky/casual. I think the boots might be a bit more casual than the Mary janes but either would be a good choice.
As for bags, maybe something slouchy?
Or something like this?
Something with texture?
ugh my computer is being so slow right now but I hope that helps. Since the rest of your outfit is fairly plain you can always get away with a more flashy bag or jewelry and still look laid-back.