which the child likes and is good at.
I think the parents have to be serious at the young age. For every new sports, even the ones only for try out, parents should choose a good/serious club or team. If necessary, using private coach at early stage is a good idea. This is similar to learning piano, private teacher is very important. When the child becomes good at certain sports, he or she will show interest and dedication to training, which results in better performance.
In general, I think the parent's role is to help kids into the virtuous circle.