An outdoor summer wedding is romantic, but it can cause panic with wedding guests trying to decide what to wear. Here, a guide to summer wedding attire: Do * Take your cue from about the level of formality for a summer wedding from what the invitation says. Only an after six, “White Tie” or “Ultra Formal” would require a long gown (and those invites are very rare). * Choose pretty florals or yummy colors (pink, yellow, blue) for daytime or outdoor weddings. * Dress up more for weddings after 6 P.M., but still keep your look summery (sleeveless dresses, strappy sandals, glowing skin). * Do keep hairdos under control in hot weather with soft updos or pretty hair barrettes. Don’t * Don’t wear white because it competes with the bride. * Don’t wear hosiery, heavy makeup or chunky jewelry in hot, humid climates or you’ll melt. * Don’t dress too sexy — belly showing or lots of cleavage — because it’s not an appropriate occasion to dress like a tart.