If "run regularly" is on your tentative list of New Year's resolutions, you may find Runner's World's (US) What Should I Wear? calculator may help you pick appropriate attire.
Just bung in the temperature, wind speed, and sky conditions, then add how you prefer to feel when you run (cool, in-between, warm) and it'll suggest what you should wear. It's interesting to note, it doesn't recommend particular shoes, so these must be optional 🙂
On the face of it, this appears to be a another silly web application, however for those new to running, the added stress of worrying about what to wear could be the deciding factor between going for that run, and not.