If You join a server, people will not see your skin as long as they don't have that skin installed already.
But if you would be hosting a server, and put Autodownload ON, people would download that skin and other stuff they don't have already, to be able to play on your server.
So my suggestion is not to use "minor" popularity skins in public servers, since most people only use skins like Vader, Maul and Boba/Jango Fett models/skins as extra skins.
But of course if you want to see your skin then choose any you want, but don't expect all other people will see it. They will see their default skin on you, if they don't have the skin you chose.
Hope that cleared your mind a bit