This little guide will walk you through installing custom skins, specifically player skins, even if you have a cracked Minecraft.
Download your skin. You can get skins from many different places, some examples are:
The Skindex - Minecraft Skins
Minecraft Skins | The BEST Free Minecraft Skins
Latest Minecraft Skins
And of course, the MC forum:
Skins - Minecraft Forums
Make sure that your skin is in a .png format. Not .JPEG, .gif, .TIFF either. .PNG ONLY. Right click your skin and go to properties to make sure its in .png.
Rename your skin to
No caps, not spaces, just "char" Your file is already in .png format, so there is no need to add .png on the end. "char" is all you need.
Navigate to your .minecraft/bin folder. If you need help finding it, refer HERE
Open your minecraft.jar with an archiver such as 7zip/Winrar
Open the "mobs" folder.
Drag your custom "char" file into the mobs folder inside your minecraft.jar
Quit out, and test in your game.
Some errors you may come across with it not working, are probably caused by a custom texture pack interfering with what you are doing. If you have a .zip folder in your texturepacks folder that you are using in game, make sure that you put your custom char skin into that instead. Make sure its in a folder called mobs. If there is no folder called mobs in your custom skin pack, make one and put your custom char in there. The same goes for HD packs that you are using the patcher with.
Note that this tutorial works for pretty much any texture pack, but it is far easier to just paste your pack in the texture pack folder, or if its HD (>32x32) use a patcher, which will do this for you.
The reason I am posting this in the texture section instead of the Tutorial section, is because this related directly to skins far more than other things in there. People would look here in the texture section for help on textures before they do in the Tutorials section. This is not a general tutorial, but something specific to skins/textures, and belongs here. If whichever Mod is watching over this section would like to sticky this, it would cut back on a lot of questions being asked. If not, it will probably get lost here in this section, bumped off the page etc, and people wont be able to see it anymore, making it useless. So if no sticky, feel free to move it to the tutorials section anyways.