The two-piece suit (skirt and jacket) is a familiar and timeless business standard. By changing your blouse or sweater top you can change the look of your suit. Changing pantyhose color and shoes is another inexpensive way to change the look of your suit.
Chose solid colors or subtle weave patterns or plaids (test patterns by looking at the garment from across the room - a good subtle pattern will look solid from a distance.)
Women can wear wool, wool blends, or quality micro fiber but should avoid acetate / rayon blends which may not be as comfortable or wear as well as natural fibers.
To save money buy one or two jackets with matching skirts and then purchase several different skirts that also go with the jackets. Skirts and jackets do not have to be identical for everyday business wear, however, a matching matching business suit is always the best choice for interviews, meetings, and more formal business events.