I'm going to edit that with "do NOT wear high heels if you don't know how to wear them." I wore 4" pumps with a skirtsuit, but that's because I wear heels enough that I can run a block in them if I have to. My roommate wore 2" pumps with a thicker heel because she doesn't wear heels as often as I do. If you NEVER wear heels and don't know how to walk in them, you're going to look silly - stick with a nice pair of flats. If you think you might wear heels, practice wearing them around your city/town before you leave so that you're sure you can handle them. If you're nervous about wearing heels, listen to your gut and don't wear them.
In terms of advice on what to wear (sorry if I already posted this - don't feel like going back and checking), I really like Dr. Isis' advice on shoes: http://isisthescientist.com/2012/01/04/ask-dr-isis-hot-interview-shoes-and-more/
My advice for this is to avoid anything too tight. Doesn't mean yo uhave to wear a burlap sack, but a looser-fitting sweater/turtleneck will look a lot less provocative. You can even try a v-neck with a button-down underneath! You can also try to wear the skirt with flats instead of heels (don't know if you've done that already), since heels tend to accentuate curves and all.
Also, my suggestion for button-down shirts for any size woman:make sure your boobs aren't popping out. I've seen a lot of people who are clearly "between" sizes in the chest area (a small is fine everywhere except boobs, but a medium seems a little too loose, for example), and when they opt for the smaller size, they get this really awkward fold-out around their chest area through which you can see their bra (hopefully that phrasing makes sense). Check for itt when you're shirt-shopping, and when in doubt, go a size bigger!
My roommate and I both went with the method of tucking our shirts into our tights for the interview - yes, I know it sounds really sexy, but it helps to prevent your shirt from riding up and looking baggy and weird; it also makes it look less bulky if you tuck it in right, so you can't see the lines through your skirt.
</advice>....back to work!