Installing Skins

okay so i know how to install skins but sometimes my skin doesnt work right. sometimes the hands are missing, sometimes when i join a game the models are only wires, sometimes the skin is pink and black, or sometimes they work for a bit then the gun dissapears. also sometimes my gun sounds dont work. i install everything properly but whats wrong? im thinking it has to do with the scripts? the game-sounds-manifest.txt one.. i only need one right? because all of those are the same? or do i have to rename each one so that i have multiple ones of those in the script folder from each skin that i download? please help me.

Drag & Drop. It's not rocket surgery.