The groom has two jobs: to look the part next to the bride, and to last many hours in his outfit. So get the basics right first. The jacket must not pull across the back, about a centimetre of shirt cuff should show below the jacket sleeve, and the collar must not slip out from under the bow tie. In photographs, these details show far more than the colour of the pocket square.
For a winter wedding, a slightly heavier wool works well. Wool breathes, so even a heavier cloth copes well with a warm venue. In summer, weight and breathability matter more, but the lightest cloth is not always the best: very light wool creases faster, and that shows at once on the dance floor and in photographs. Choose a cloth that holds its shape.
A waistcoat is practical if your jacket often ends up on the back of a chair, because your waist still looks tidy. It must fit well, without pulling at the buttons, and it must not make you too warm, which you will feel quickly on the dance floor.
The most elegant way for a groom to stand out is a perfect fit and quiet confidence. For a subtle accent, choose a black bow tie in a different finish, matt instead of satin for example, or a boutonnière in the colours of the bride’s bouquet. Contrasts that shout across the room are the details that date fastest in photographs.