Marrying a dark green sweatshirt with charcoal chinos is an on-point option for a relaxed but seriously stylish look. If you wish to easily dress down your outfit with one single item, why not add a pair of white and navy athletic shoes to the mix? It's a viable pick if you're piecing together a standout ensemble for unpredictable fall weather. When it comes to casual fashion tips for 30-something gents, this look suits almost any gent.