The well-finished face

What is a new outfit without an up-to-date makeup? A not very effective use of one's time and effort, some might say. With makeup so much a part of the whole style picture, a change of face by way of appropriate new cosmetics is practically a necessity for style-conscious women.

Cosmetics take their cues from fashion trends, and this season's color selection offers a number of harmonious complements to Brideshead-inspired, lady-of-the-manor clothes, rich renaissance looks, and fragile Victoriana, as well as black-tie dressing and more opulent forms of evening glamour.

Although lip and cheek colors are more vivid, there is a tendency in some quarters toward the paler face. Fine loose powder, the kind that comes in boxes with a fluffy puff, is having a revival, with two houses making a special point of new face-powder products. Chanel's ''Les Extremes'' line includes a gossamer-textured group of powders intended as the finishing touch all over the face. The tints have a mauve, peach, or opaline cast and contrast with this maker's palette of scarlet or magenta lip rouge and nail lacquers. Estee Lauder's transparent face powder, in ecru, gives a warmer look, combined with cherry, coral, chestnut, or raspberry lipstick and coordinated blushers, some of which have a violet cast.

Achieving a natural glow is the aim of Lauder's ''Country Manor'' line. The formula for their new liquid makeup is lighter in texture, calculated to give a porcelain finish. For highlights on the cheekbone or the outer brow, the company offers a transparent blush stick, called ''Violets Under Glass,'' which adds a hint of mauve.

Violet casts also run through the day and night Lancome selections, ranging from dusty rose to freesia, a purpled Florentine red, and plum. Periwinkle blue and royal are represented in eye shadings for evening. Differentiation between makeups for day and for evening, with separate lines for wear in natural and in artificial light - continues to be a point with many manufacturers. Ralph Lauren's sunny country tones for daytime stress brick, peach, and red clay - a palette not too unlike the russets and other harvest colors favored by Charles of the Ritz in that company's new ''Fall Foliage'' collection.

Black and white being a continuing classic combination for after dark, Lauren suggests luminous colorings based on ruby rose and pink for contrast. Shisheido's nighttime look stresses black and white with brilliant red, in a modern interpretation of traditional Japanese theatrical makeups. Other houses have a gamut of rich jewel tones that have added shimmer. (Metallic makeups are still in vogue, but tend to be a lot less glittery this year.)

Eyes remain the focal point of the well-finished face. Slate-green, muted earth tones in ocher and beige, deep burgundy, amethyst, smoky teals, and navys are among the latest hues. Many houses offer yellow eye shadings (Chanel's entry is ''Neon-Electric Yellow''). These, one suspects, would best be applied after an instruction session with an expert at the cosmetics counter.

Layering shadings of different colors and blending them together, along with smudging eye liners to avoid a hard look, is still the approved method for eye enhancement. In place of black, there are several alternative colors in eye pencils to try - Bordeaux and inky green are two of them. For a more-defined upper lid, Madeleine Mono, the eye-makeup specialist, has brought out a new onyx liquid eye liner.

No single hair style has come through so far as the coiffure of the year - short, medium, and long are all in the running. Geometric hairdos somewhat like Vidal Sassoon's 1960s cuts are popular with certain New York models, but others cling to their masses of long, undulating locks. The swept-back classic coiffure with a braided chignon has its adherents. Cropped short hair reminiscent of the 1920s is also chic. For the young and ''with-it,'' Jean Louis David advocates ''unstructured'' cuts. The hair is kept short in front and shoulder-length in back, snipped into points, then given a foundation permanent. The end result? Rather like a shag that has been curled and brushed out.