This combination of a v-neck t-shirt and blue skinny jeans is on the off-duty side yet it's also seriously stylish and really dapper. Charcoal derby shoes are a guaranteed way to breathe an element of polish into your look. You're guaranteed to always look stylish even despite the oppressive heat if you have this ensemble as a last-minute grab. When it comes to casual clothing for guys in their thirties, this outfit is ideal.