What is a good dress i could wear to a wedding?

Hi you should wear a cocktail length dress. Depending on the location, you can decide what design or shape you want, a summer dress can look formal with a nice cardigan or jacket. If you want to be more formal, you can go on sites like forever 21 and look under the dresses section, they have subsections for dressy, casual, family events and just get some ideas there. For lighter olive skin, a light purple eyeliner and white shimmer shadow on the inside corner of your eye would be really pretty! You should really make sure whether you're part of the wedding or not because if you are it's your sister's choice as to what you would wear. Good luck!