neat question. I also have no wardrobe but i work part time so i need to replace asap.
part of my answer might depend on your body shape.
I'm not fashionable so fresh modern clothing puzzles me,
I definately think some loose knit skirts could be very cute. and i find dresses to be a nice fast casual day time look. not a pencil skirt but a demin fitted dress with some boots or sandals, or an oxford ish type shirt dress.
. I think 2-4 paris of jeans is good, I like the dark denim.
for a while i had a uniform of v neck tee in every color and jeans w cute flats.
if you are thin, pinterest has awsome outfits that you can take a look at.
if you have some body flaws and don't know how to work them, flylady.net used to have a sister site like mrsmarty pants or something like that. that you could sign up for and pay to see make overs on real people at real stores.
often macy's type stores have personal shoppers you can inquire as to the cost. I have a consigment store that offers a fashion consultant for free. so that might be an option too.
personally, i don't think i would do the leggings I think basic bottoms will take you farther and mixing up your tops will freshen your look more cost effectively.
but what the heck do i know.