#1 and #2: Nice compositions in both, but arm cut off in #2. Overexposed dress in both, flowers appear really weird (as if oversharpened in PP).
#3: Lovely pose. Horizon is tilted. As mentioned above, horizon/head conflict. I'd clone out the bird droppings on rail. I think your sensor is dirty, too.
What's the best way to ensure that a bright white dress such as this one isn't over-exposed, but at the same time keep skin tones looking nice? Any good tips or tricks?