Ok...you're head to the interview. Here a couple of real quick things you can do and/or check.
1- Spit out the gum (before you leave home otherwise you may forget)
2- How short is that skirt? Bend over to see if they'll see too much.
3- How much cleavage is too much? Will they be looking at you or down your shirt?
4 - Cover up visible tattoos. Many companies have a tattoo policy, It's o.k. to have them just keep them underwraps until you know the policy.
5- Is that dirt under your nails?
Can you add to this list?