The key to dressing for a concert is to base your outfit on the kind of event you're attending. Before choosing your ensemble, take into account the concert's venue -- indoor or outdoor -- and the level of formality.
Indoor venues tend to get hot and stuffy. To avoid looking like a sweaty mess, keep your outfit light and well-ventilated. For girls, a lightweight above-the-knee dress or a high-slit maxi dress would be ideal. For shoes, opt for strappy sandals or even sneakers as, sometimes, indoor concerts can get pretty messy, so closed-toe shoes would be good for keeping feet clean and protected from spilled drinks or other people's feet. Guys can opt for shorts and a loose tank top or tee. Sneakers would also be an appropriate option for this combo.
Outdoor concerts offer more options for attire. For an all-day outdoor concert, a dress and flannel combo works great for girls. During the day, just tie the flannel around your waist. Then, once it gets dark and chilly, throw on the flannel as a jacket. This idea also works with cardigans. Both guys and girls can tie a cardigan around the waist with a tee and shorts or pants combo during the day and then wear the cardigan at night. For a nighttime concert, jeans with a tee and a leather, denim or parka jacket would work for both genders. Accessorize with a neutral-colored beanie, and opt for neutral-colored boots or sneakers -- just make sure they are comfortable so you can dance blister-free.
To shade your skin from the harsh sun in the warmer seasons, opt for a sunhat or baseball cap as an accessory. Sunglasses and sunscreen are outdoor concert staples as well.
For a more formal affair, such as a classical music concert, you can go all out. Girls can wear something as fancy as an evening gown and heels, or go a little more casual with an A-line dress and a blazer or fitted cardigan. Guys can go in a full-on suit or wear trousers with a crisp button-down and dress shoes.
Casual concert attire for both girls and guys can build around jeans and a tee. Opt for distressed jeans, blue denim or colored jeans. For tee options, wear a plain neutral colored tee -- which would be mandatory if you go with colored jeans -- or a graphic, colored or patterned tee. Dress up the look with various hats: beanie, boater hat, fedora, bucket hat or wide-brimmed hat. Layer with a scarf, cardigan, flannel or light-weight jacket. For shoes, girls can wear sandals, boots or sneakers. Guys can wear boots or sneakers as well.