For an ensemble that's truly GQ-worthy, marry a dark green waistcoat with a long sleeve shirt.
Dark Green Waistcoat with Long Sleeve Shirt Dressy Warm Weather Outfits
This combo of a dark green waistcoat and a long sleeve shirt is a lifesaver when you need to look really sophisticated. Clueless about how to complement your getup? Wear brown leather oxford shoes to class it up.