Work on low gravity, agility, hit the gym, work on mental aspects such as determination and aggression. Attack from wide and seek open spaces. Focus on first touch rather than technique since he will rely on that extra time to adjust his body and move quicker than the defender. Finally, learn to roam, finding the right pockets in the right time is important for everyone but vital for smaller players.
That's from the top of my head. Messi isn't big, he is not strong. He's bigger alright but remember when he came up? He could still damage anyone and any team. I'm not saying this kid will go the same lengths but if he sets up a process he can still become a serie a player. I still think Giovinco would have been a decent rotational player if he didn't see himself as a starter and striker. Size helps but tiny players can still trouble you, but they have a harder road in front of them. Obviously, these are just my thoughts and I have no real argument to put forth to support them.