1.  Presentation counts.
2.  Casual shouldn't mean slovenly.
3.  Dress as you want to be seen; serious
                                                  upward - bound
                                                  ready to meet clients
The traditional look includes:

--a skirt that hits just above the knee
  slacks or perhaps a pantsuit
--simple jewelty
--just a hint of makeup
--polished flats or moderate heels
--pantyhose may be the office standard.  Ask.
The following information was written in an article by
Scott Reeves in Lifestyle magazine.
According to Kim Zoller of Image Dynamics, 55% of
another person's perception of you is based on how
you look.  Her suggestions for interview attire are:

solid color, conservative suit
coordinated blouse
moderate shoes
limited jewelry
neat, professional hairstyle
tan or light hosiery
sparse make-up and perfume
manicured nails
portfolio or briefcase.