Although it is quite all right for one's suit jacket to be of the same color fabric as one's skirt this spring, the mismatched suit wins more points for fashion know-how.
Dark with light or bright with somber are the best contrasts in the mismatching game. But a fine check, a contrasting texture, or a twin print used in reverse order is good, too. In some cases, a patterned wool of two or more tones will be combined with a solid color from the pattern; in others, a light jacket will be piped with the dark of the skirt.
As to proportions: The important point is the shoulder -- rounded, and either padded or widened by way of pleating or gathering where the sleeve is set in. If the waist is indented, it is not quite so nipped in as heretofore, and it may or may not be belted -- as you wish.
As to styles: Last year's skinny shirt with the high slit has been retired in favor of an easier cut. Most straight skirts have gentle gathers or pleats at the waist. There is also a wide selection of swinging flared and pleated skirts for those who like a bit of a twirl when walking.
Jackets tend to be either on the short side or hip length: boleros and spencers on the one hand, and straight double-breasted tunics on the other, although the cutaway that ends at the hipbone is also on the approved list.
As noted elsewhere, the suit with a diagonal closing which, when opened, gives the effect of the lapel (customarily faced with contrasting color) has much cachet. It was, after all, first presented by Giorgio Armani, the Milanese designer of great prestige.