Tutoring will be important - Determation, Ambition, and Proffesionalism are equally important when it comes to player development. A tutor can also pass on PPMs, but make sure they are ones you want.
Playing time will matter once they turn 18 - they need to play at a competitive level. Prior to that, facilities matter more and you are in good shape there. I've had great luck with youth player development by giving them matches, even as young as 16 years old, but the level of play is usually not as high as the Premier League in my saves, so that might be difficult.
Like McMinn says, the Roaming Playmaker is a good choice because it trains a lot of skills. Don't be afraid to switch the role you are training them for every few months to target different skills. Once his attacking skills reach a good level, you might want to switch to a more defensive role for training so he grows in those skills, even if he won't ever be used in that role.