If the situation allows a casual look, go for an olive bomber jacket and a crew-neck t-shirt. Add a pair of tobacco leather sandals to the mix to infuse a dash of stylish nonchalance into this look. This look isn't a hard one to pull together and it's season-appropriate, which is important when it's blazing hot outside. This pairing proves that moving from your 20s to your 30s is no reason to shed casual style altogether.