“You cannot climb the ladder of success dressed in the costume of failure.”

So said the late Zig Ziglar, the world famous motivational speaker, business consultant and author. While the quote has multiple layers of meaning, a face-value reading is especially on point for promotional product sales professionals: Your chances of success increase when you’re clothed in a manner that projects professionalism, confidence and capability.

Indeed, the influence of dress on success is no empty cliché. Growing research suggests something happens on a biological level when we’re outfitted well. A study reported in the December 2014 Journal of Experimental Psychology found that men who wore suits during negotiations won more profitable deals and had higher testosterone levels than men who negotiated while dressed down. Meanwhile, a paper published last year in Social Psychological and Personality Science found that wearing formal business garments enhanced abstract thinking, which is essential for creativity and long-term strategizing. The effect was tied to feelings of power, the experiment suggested.

With scientific studies backing up the long-held common-sense thinking on dress, it’s clear sales professionals who attire themselves well have an edge. To make that advantage your own, we present an ultimate garmenting guide for salespeople. From getting the right fit to dressing best for your body type, to advice on accessories, fashion faux pas to avoid, clothing maintenance hacks and more, we’ve got the tips that will have you dressing for success.