Insimenator.org

In layman's terms, a Sim's clothing consists of two parts: the texture (commonly "skin" or "recolour") and a mesh.  Meshes are always required in some form or another - some are already in the game as they were made by Maxis, these are named "default" skins/meshes.  Those made by people not employed by Maxis are "custom" skins/meshes.

This is not to be confused with a genetic skintone.  But the same classification of "default" and "custom" still applies here as well.

The custom clothing will show up in categories with a * on the corner of the thumbnail preview.

To use the genetic skintones - in sections 1 of the Create-a-sim, create-a-student, or create-a-family (called different names in the various versions of the game) you will see the skintone colours -- to get to Marvine's and my skintones you need to click the * you will find there by the darkest skintone colour visible without the *.

The genetic skintones by Marvine & myself usually require meshes; these are generally included in my RARs with the skintones.

So if you want to use the clothing you see in my posts, you need to have the Skin part and the Mesh part; the colour of the flesh is not important.  These clothes will work on any colour of flesh default or custom.