For the actual shoot, the top half of your body will be more emphasized than the lower half, so the tops you bring are more important than your lower body and footwear. That being said, you want to think about the type of images you will want in the end and your clothing should reflect that. Do I want to appear more formal or more causal? If putting together a complete outfit puts you in a better mindset for the shoot, I would say, by all means, dress to impress. But once again, your comfort is more important, in my opinion.
Here are a couple of things to keep in mind when choosing your outfits; no intensly white or light colors (it will wash out your skin), no logos (though we can cheat if need be), and patterns can work (nothing too hectic). I would say neutral tones are fantastic, bright colors are okay, but nothing to obscene; the whole point is for the focus to be on you. Also, we want to see you on your best day, so you should wear clothes you are completely comfortable in.