Aerith's most prominent feature is her pink dress, so put extra work into finding the right fabric and shade of pink. An oxblood-colored bolero is the normal accompaniment. Carrying around a basket of flowers is important, as that is how Aerith first appears in "Final Fantasy VII." Another good prop is a bo-staff or similar pole.
Large brown boots along with large bangles on the wrists should be included for the most authentic look possible. Keep in mind that the above tips are for the version of Aerith featured in the original "Final Fantasy VII." Her other, less famous attire worn in the events before "Final Fantasy VII" consists of a simple white-and-blue dress. If this is the preferred costume, omit the staff or other pole-type weapon. The basket full of flowers would be the best replacement prop, as her character never takes part in any battles while carrying it, though she is known as a flower girl from the slums for the entirety of the series.
A bright pink hair ribbon should be present regardless of the version being cosplayed. For extra authenticity, add a white ball within the ribbon to represent the magic materia given to Aerith by her mother. Use hair gel, hairspray, egg whites or the lather of inexpensive white soap to achieve her signature forked hair look. Remember to back-comb vigorously.