This tutorial will show you how you can fix missing sounds on skins after patch 11.20 broke a lot of them.

Tutorials
Updating remodels after patch 11.3
This tutorial teaches you how to stop remodeled custom skins made before patch 11.3 crashing your game.

Tutorials
Updating old Wooxy skins
This tutorial teaches you how to update skins which are in .wxy format.