I'm assuming you're a girl. I'm a 20 year old girl and I usually wear khakis, these pair of nice black flats I have, a small black purse and at least a nice plain t-shirt but wearing a blouse or a button-down shirt is even better. Basically, pants that aren't blue jeans, so solid colors like khakis or gray or black slacks, etc. And a nice top. I've also heard of wearing dresses to interviews but I hate wearing dresses so I wouldn't know.
if your a girl I would wear dress, or a skirt and nice shirt, or you could even wear dress pants and a nice shirt. You could wear something like this: Something similar to these. Good luck! :)
suit (if your a guy)... you definitely dont wanna be underdressed and being overdressed isnt a bad thing at all.. for a girl.. no clue
it depends on the job and on your gender. in general, dress upwards from your normal style
suits,skirt,maybe shirt all seem good.
