Search for similar styles on the internet to give you some further ideas. When you see your hairstylist for your trial, they can also assist you with what suits your face shape and also what will compliment your dress. They will look at the style you have chosen and check the suitability of your hair for that style.
Sometimes, if there is not enough hair, extensions can be used to fill out the hairstyle and add length and volume.
If you have the kind of hair that gets frizzy in humidity then an up style could be the way for you to go. Same if your hair is renowned for not holding curls. Is your hair going to be limp and lifeless with a down style after a few hours? Is an up style too formal for your dress style?
All of this should be considered when choosing your style. Your professionals can help you with that.