While shoes are the only essential item of clothing needed to begin running, you want to dress comfortably, if not fashionably. For your first steps as a walker, jogger or runner, you can grab almost anything out of your clothing drawers. Various synthetic fabrics work better than cotton.
Most runners prefer socks that are thin and lightweight and ankle high.
Running socks are probably your least expensive item, but test whatever pair you purchase in a few workouts before filling your drawers with dozens more. Floppy shorts with a slight sidecut, usually of a synthetic fabric, are popular with most runners. Running shorts come with built-in underpants. You may or may not want to wear your own underwear beneath. A simple cotton T-shirt will do.