Begin with the invitation rather than a dress code guess. If the couple specifies a level of formality, use it as your starting point; if not, consider the venue and time. A garden ceremony, a city restaurant, and an evening reception may call for different fabrics and levels of polish. When details are unclear, asking the hosts or another guest is more useful than assuming.
Think about the whole day. You may be standing, walking on grass, sitting through a long meal, or moving between indoor and outdoor spaces. Choose a length and hem that feel manageable, and consider a wrap or light layer if the temperature may change. Shoes that you can comfortably wear for several hours are part of the outfit, not an afterthought.
It is generally considerate to avoid white or shades that closely resemble the couple's outfits unless the invitation says otherwise. That still leaves plenty of room for color, print, and personal style. Check whether a pattern or embellishment feels appropriate for the setting, and make sure you can move and sit easily.
Before the event, try the complete outfit at home. Check the neckline, straps, hem, and pockets, and confirm that the fabric is comfortable against your skin. A dress you can enjoy wearing is a better choice than one that only looks right while standing still.
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