If you are the bridesmaid of the bride, if you want to be relatively formal, you can buy a smaller bridesmaid dress, which can be short and light, such as champagne, white and light blue. Or a dress that matches your sister's wedding color. Remember not to be too dark or too bright, the bride will think that you are strengthening her style. If you don't want to wear a formal bridesmaid dress, you'd better wear a dress or a double skirt, and the color should be light. If you're not a bridesmaid, just attending her wedding, that's easy to say. All kinds of nice clothes will do.