Would tell him/her as I do to many of my juniors and young riders, to not rush and burn stages, it's not jumping high , because now anyone with a big budget can jump a descent 140.
But it's jumping well, working a LOT flat work and not just jumping, to ride as many different horses possible and not just knowing how to ride 1 style of horse, to learn about managing a horse, how many times a week the jumps, flat, longe, etc..
Get involve with the psychology of the horse so he can manage different kind of horses .
That will make the difference between a young rider and the good young rider
Excuse my English, I'm sure I have a lot of mistakes but I'm trying ;)