Re: how to install skin on the sims 3

@Splotchish  If the skin is a .zip file, you can extract it with Windows; .rar and .7z files do need an outside tool such as WinZip.  In any case, right-click on the file to show the options, for example Extract for a .zip file or WinZip > Extract for the others.

What you do next depends on the type of file you wind up with.  A .Sims3Pack file goes into Documents\Electronic Arts\The Sims 3\Downloads, and then you open the launcher's Downloads tab and install the skin from there.  If it's a .package file, it's installed like a mod.  Here's a guide for setting up the Mods framework:

https://modthesims.info/wiki.php?title=Game_Help:Installing_Sims_3_Package_Files/Setup_and_Files

One important note about custom skins is that you can have only one default skin per category of sim: it's the "default," as in, all sims get assigned it unless you choose something else.  Multiple default skins will conflict with each other, and only one will end up loading.  (This is only true for skins within the same category, for example you can have a default skin that's only for females and one that's only for males, and they should both work.)  You can have as many non-default skins as you like.