If you want to learn how to better teach new users about your product, GDC talks about video game tutorials are one of the best resource you can find
Oftentimes it's less jarring to have an invisible tutorial though (a level made to exploit the new gameplay element / feature). But it depends on what you want the user to learn and the type of videogame; I don't mind a guided tour in more strategic games (RTS, turn by turn RPG, ...).