Well, there are a few different ways to do that. You could reduce your wardrobe to a few classic pieces in neutral colors and mix and match those things using accessories like scarves, jewelry, etc...
Think of the things which can be multi purpose first then work from there.
For instance, a kick @ss pair of black pants. Those can take you almost everywhere....wear with a bright colored fitted t shirt for casual day....nice blouse for a night out, modest blouse camisole and blazer for any meetings or job interviews etc....
Or a nice pair of khakis too can be dressed up or down.
If skirts are your thing, I would seek out a couple of skirts that can be worn bare-legged with sandals in the summer or spring, or with tights/hose/leggings in the winter... in other words, a really light cotton hawiian print may not be as versatile as something like a knee length/slightly a-line light denim (not light as in color, light as in weight)....
Speaking of denim, that is really in right now and can be dressed up or down as long as you aren't purchasing the trendy distressed super short mini jean skirts and such...
I always begin with the bottom when thinking of my wardrobe because those tend to be solid colored (except maybe skirts) and to most people, black pants are black pants ... they are more likely to notice if you've worn the same shirt 3 times in a row somewhere than if you've worn black pants kwim?
I would begin with something like:
1 pair of flattering jeans (nothing too trendy, but tapered leg is 1989)...so I'd go bootcut midrise in a medium wash... nothing too distressed....
1 pair of khakis
1 pair of nice black pants
1 "little black dress"... it doesn't *have* to be black.. the idea is more like a dress you can wear to many occasions... it can look demure and flattering at church, it can be spiced up for a date with your partner, it can be worn to a wedding with the right accessories... it isn't a *must* in a wardrobe but it does cut down on "what am i gonna wear to this thing I dress up for twice a year"
Then the shirts would be in the same "family".... that is where I tend to add my color. I would begin by buying shirts that went with both of the skirts, as skirts are usually where patterns are... but if you have a jean skirt that wouldn't matter....
A fitted crisp white shirt goes with absolutely everything.....khakis, jeans, skirts, even the right pair of shorts. I say fitted, because it looks better if it is tailored to a woman's shape (imo).
I would get a couple of bright colored v neck T-shirts too... that is where I have my color (other than with accessories). Some people don't care about color or prefer more muted tones, that makes it even easier. Also if you get a higher quality "t"shirt, it can take you further with regard to *dressng* it up.
Okay so with what I mentioned you may have this (as an example)
1 Jeans with crisp white shirt
2 Khakis with bright v neck
3 khakis with v neck and crisp white shirt over it
4 skirt with other v neck
5 v neck with black pants, cardigan
6 black pants white shirt, other v neck under it
7 patterned skirt with v neck to match
8 jean skirt with modest camisole
9 jeans with blazer and camisole
10 black pants, camisole, cardigan
11 v neck, jean skirt white shirt
so you have already 11 outfits with only 11 pieces... that doesn't count accessories you can play with, or other outfits you could potentially create.
I tend to have a pretty simple way of dressing though -- if you want to get all trendy and *of the moment* (not you, just general you)... of course you would need loads of stuff. It can be played with if you are in a place with harsh winters etc... Just examples...
(2) t shirt
blazer or light (as in weight) nice cardigan
Hope that helps