The best choice of fabric for a suit is pure wool or wool-blend in navy or charcoal gray with or without pin-stripes. Other styles such as muted plaids and tweeds in neutral colors are acceptable.

Wear traditional cotton or cotton-blend shirts with long sleeves and straight or button collars. White and light blue are recommended for interviews. 

The best fabric for ties is silk, followed by polyester that looks like silk and silk-polyester blends. The tie should just reach your belt buckle. Choose from classic polka dot, paisley, or repetitive patterns in dark colors. 

The best shoes for an interview are leather or simulated leather lace-up shoes, like wingtips. Choose dark colors like black, cordovan, or dark brown. Dress socks should match the color of your slacks or shoes. 

Watches, wedding rings, and conservative men's rings are appropriate in any situation. Steer clear of items like bracelets and earrings, which convey a more casual look. Facial jewelry is inappropriate. 

Personal hygiene is essential in all professional settings, including clean and well-groomed hair, clean healthy nails, and well-groomed facial hair. A short, conservative hair style is the most professional. If you have a beard or mustache, groom it daily. In particular, your mustache should be well above your upper lip.