Wear the right T-shirt. Any color, preferably featuring a print relevant to geek/nerd culture. Comic book characters and symbols, science maths and computer jokes/references, science fiction & fantasy cartoons, movies, television series and games, anime/manga, video games. Plain t-shirts are good for layering. Try a plain bold colour like purple over a striped long-sleeve, and plain white t-shirts if you prefer to wear these under dress shirts.