I don't wear cycling specific clothing either, although I might get a fancy rain jacket this winter (after commuting for more than 10 years). If you're a woman and work in a business casual setting, most women's work clothes are very easy to commute in and much more forgiving than men's work clothes. Avoid pencil skirts, and if you think you're going to sweat a lot, wear a different shirt to ride in than you will wear at work. If you're wearing a skirt, throw a pair of leggings or bike shorts underneath and remove when you get to work. Almost any shoe will do--I regularly ride in heels. (If you are using toe clips, make sure that they don't scuff the leather of your shoes.) Wear dark colors on slushy or muddy days to hide any dirt that gets thrown up on to you from your tires. You don't need rain pants if you wear skirts in a synthetic fabric that will dry quickly (does not need to be a performance fabric or from a fancy catalog like Athleta) on rainy days, and change into dry tights or leggings at work. In the winter I keep a nice jacket in my office so I can wear something practical on the ride but then have a nice-looking option if I need to go somewhere during the day looking like a grown-up.