This section is from the book "Clothing For Women: Selection, Design, Construction", by Laura I. Baldt. Also available from Amazon: Clothing For Women: Selection, Design, Construction.
The first thing to be considered when planning a suit of underwear is the type of garment to be made. Dear to every woman's heart is a dainty bit of lingerie, and it is right that it should be so, but her care should be that she choose the sort of garment (1) that will be in keeping with her outer apparel, (2) not strain her purse, nor (3) burden herself or others with the care of laundering.
I. Type. - In choosing the type, fitness is of great importance. For instance, for wear under dresses of wool, silk or linen, the corset cover or underbodice may be made of firmer material, and less elaborately trimmed than for wear with lingerie waists and summer dresses. White cotton petticoats, either plain or trimmed, are not in keeping with the dark wool, silk, or linen dresses. These bespeak colored silk or cotton petticoats. By no means, however, need there be absence of decoration, but this should be of simple kind. On the other hand, for wear with lingerie waists, one instinctively desires a little more elaboration on the undergarment. This instinct needs to be held in check until one learns how not to mar the pleasing effect of the outer-garment by the selection of the under. How often one sees a very attractive waist, simply trimmed perhaps, with tucking, lace or hand embroidery, beneath which shows a corset cover adorned with rows of lace insertion or huge medallions, which immediately contradict the graceful lines and curves of the waist. Because of the quantity needed "to trim" the undergarment, the wearer may have used inexpensive lace of large pattern. Better far to have confined herself to less lace of good quality and recognized pattern, that would in no way irritate the beholder's sense of the fitness of things. Just here, in speaking of the effect of decoration, it may not be amiss to mention neck and armhole lines in corset covers and underbodies. A round neck cut as low as may be desirable is usually more pleasing to the eye when seen beneath the waist than is the square or V-shaped line. The latter seem to be continually at variance with the lines of the outer-garment, or where the back of the waist is plain, the undergarment stands out too prominently. Care must be taken in marking the line for a round neck, to have the lowest point in the back in proportion with the length of the back. The curve in the front should always drop below the curve in the back. The undergarment must be subordinate to the outer; in other words, serve only as a good background for a pleasing picture. Again, the picture should not be marred by the appearance above the corset cover of the top of a refractory under vest carelessly adjusted.
It is to be remembered, then, that the design for corset covers and underbodices should be simple in line and decoration, the latter confined mostly to the neck and armhole, except perhaps fine tucking or simple stitchery on the front, richness to be obtained by the use of fine material, dainty lace of good quality and pattern, embroidered edging, insertion and beading, having similar background to the material of the garment.
When underwear is to be made up in sets, the ornamentation should be similar throughout, and the same lines used on the neck of corset cover and night-dress. When odd garments are being made up, if a square or V-shaped neck is desired, this idea might be carried out in the night-dress.