To choose the best nylon slip, first decide whether you would prefer a full or half version. A full slip may double as a nightgown, yet a half slip is going to be cooler in warm weather. Length is an important consideration when buying a nylon slip because if it's too long, it will show at the bottom of a skirt or dress.
A snip-away style is a great solution to the problem of having the right slip length, especially during travel when there may be nowhere to find another undergarment or get it hemmed. This type of nylon slip features rows of lace at the bottom. Each row may be cut off as needed with scissors to create a shorter slip length each time. There is also the option of leaving it as is with all of the lace rows intact. Of course, once a row is snipped off, the slip cannot be any longer than that, but wearing a shorter style under a longer skirt or dress isn't usually a problem.
Full nylon slips are usually the best choice for dresses, while half slips work well with skirts. Depending on the thinness of the fabric, the gathered waistline of a half nylon slip may show through a dress to interrupt its smooth line. Full slips tend to move with the dress. Half slips work better with skirts though as a full slip may ride up and puff out over the skirt's waistband. Also, nylon slips are made from synthetic material and don't tend to "breathe" well, so a full slip under the waistband of a skirt may cause the wearer to feel sweaty at the waist.
When choosing a full nylon slip, don't forget to consider the neckline. Many, but not all, full slips have a V-shaped neckline. If the slip features a wide lace trim at the neckline and you don't want it to show in the collar of your dress, it's best to pick another style. Sometimes, a lower quality full or half slip may feature lace trim that creates bumps underneath a skirt or dress. To avoid this, look for quality stitching and flat hems and seams when buying nylon slips.
The color of nylon slips to have in your wardrobe depends on your clothes and style. In general, black or dark colored slips should only be worn with dark colored skirts or dresses to avoid showing through. Darker colored slips tend to work well for evening, while a nylon slip in a light color is typically best for daytime wear.