The key is to give them choices that will make them feel comfortable, but to ultimately achieve the look you desire. It is your day, after all! Letting your bridesmaids have too much freedom sometimes backfires. It's important to define what you want. If you'd like them in floor-length dresses, be sure to tell them that. If you're wearing a strapless gown and, therefore, want them to wear sleeves, make that clear. If you give them guidelines while letting them know that you are concerned with how they feel, they will be happy to please you.
The Accessories
Okay, so the hard part is over: You've chosen the dresses. But you're not in the clear yet! There are all sorts of other decisions that need to be made. What type of jewelry should your bridesmaids have on? What shoes? Do you want them to wear stockings? If so, what color? To deal with these issues without losing your mind, first consider the overall look you would like to achieve. Do you want all your bridesmaids to look the same, or do you want their personalities and differences to show? Then think about what the most important items are to you and what pieces they likely already have.