Alexa Chung is famous for her shoulder-length shag haircut. This picture shows two versions of her signature look. On the left, she wears her shag in soft waves that fall away from her face. On the right, she has edgy bangs and natural, effortless waves.
The secret to this haircut is to have minimal layers cut into hair. Ask your stylist for thick, piece-y ends typical for the shag. If you opt for Chung's brow-skimming bangs, make sure your stylist cuts them so they actually skim the brows -- anything shorter will look dated, anything longer and you'll find yourself sweeping them to either side.
The shag works on all hair textures, but this particular look works best on hair that has natural wave to it. Find out how to get the waves on the left in this article, How to Curl Hair: The Secret to Sexy, "Beachy" Waves. To get the rough texture on the right, use a salt spray and scrunch hair as it dries. You can make your own spray with this DIY recipe or buy one. I recommend Fekkai's 'Marine Summer Hair' Beach Waves or an old-school favorite, Bumble and Bumble's Surf Spray.
This is Gallery 1. See my other galleries of shoulder-length hairstyles: