A longtime friend of mine messaged to say that she was traveling to NYC for an interview and requested some workday/interview looks. I treat my workday looks just the same as I do my weekend looks. Of course I'm more casual on the weekend, but I have just as much fun getting dressed for workdays. I don't feel as though you have to be boring at the office just because you work in a conservative environment. The key is to look professional, always, chic and put together. It's very easy to fall into a style rut of boot cut pants and button downs, which is what I see most often on girls my age. There is nothing wrong with those looks, but go the extra mile and accessorize with great shoes, a statement necklace, a colorful jacket, or hell, all three!
There are a few items in my closet that I couldn't live without for the office. High waist, wide leg pants (black, red, cobalt) are not only comfortable but they give you a long slim look no matter what your size is. I get compliments every time I wear mine.
Silk shirts, in every color of the rainbow go between seasons, can be layered with anything without being too hot, and can add a much needed pop of color. I prefer silk to cotton because they don't wrinkle as easily and they hold up better over time.
Jackets, blazers, and coats can add the final piece of effortless polish you need to tie the whole thing together.
Finally, accessories make your look shine. Depending on what you feel comfortable with and what you can get away with at the office, you can accessorize with a skinny belt or a fur collar. Skinny belts in contrasting colors break up an otherwise boxy look. A great bag is a no brainer. I like to carry a larger bag that fits my MacBook, files, etc. along with a smaller bag inside that I can grab for lunch or to run errands if I don't need to carry all my junk with me.
As far as the don't's: don't wear anything too tight, including pants or button down shirts that gape open because they are too small. Don't wear anything too short. Pay attention to the height of the slit in your skirts. No one wants to see your Britney or your Spanx at the copy machine. Don't wear anything uncomfortable. When yo don't feel you look your best, it's projected in your voice, posture, and most importantly your confidence.
Hope this helps!