Dress in a grey three piece suit and a beige floral dress shirt for extra stylish style. Complete your outfit with a pair of brown woven leather derby shoes to bring an element of stylish nonchalance to this getup. This combination isn't a hard one to score and it's season-appropriate, which is most important when it's roasting hot outside. Looks like this go a long way towards developing your style as a 30-year-old guy.