[CaptainCox]

Best is to use JSGME. Full instructions here.

- How do I install mods using JoneSoft's Generic Mod Enabler (JSGME)?
"The Generic Mod Enabler takes most of the hassle out of installing and uninstalling mods from your game."
JSGME is a free utility program to help you install and manage your game mods - highly recommended, especially if you have never installed mods before.

A - JSGME has built-in help information, but you may also find these guides useful:

JSGME guide with screenshots
How to install different mods using JSGME
The most common mistake when installing mods with JSGME

C&Ped from UBI's officail forum

The easiest way to see the structure you should pack it in is to download one of Foo's skins
Open the mod and check out where what goes where in terms of file names etc.