Skin size must be max. 500 kb, and dimensions maximum 500x500 and minimum 100x100 pixels.
Skin must be a PNG file. Skin name can not has whitespaces. After uploading skin succesfully, wait until Admin accept it.
I will not add your image if I don't like it, without giving a reason.
DON'T SEND ME SKINS WITH CUSTOM TEXT, I WILL NOT ADD THEM.
Remember that skin name must have only english letters.