How do you change the character's appearance?

You'll want to access the player itself, and find its name. Then after that, you'll need to set the .CanLoadCharacterAppearance to false, as it's set to true as default. ".CanLoadCharacterAppearance" is a boolean that determines whether or not your character's appearance loads when the game finishes loading. This code helps to override your character's appearance, in a normal script:

game.Players.PlayerAdded:connect(function(player)
	local appearanceOverride = game.Players:FindFirstChild(player.Name)
	appearanceOverride.CanLoadCharacterAppearance = false
end)