The best way to transfer knowledge and to build experience in a new team member is to put them in a leadership position. Put them in a position where they must make decisions and where they can make mistakes.
Ideally they are put in charge of a project that is outside of their comfort zone (but not excessively so). It should be challenging, but they should still ultimately succeed. You should continue to be there for support and instruction when necessary.
Putting junior people in charge makes them better. It makes them understand what is going on way above their pay grades. It makes them understand how their jobs impact higher level business goals, and is one of the best ways to develop team members.
- Put them in charge
- Give them responsibilities
- Train them by their mistakes.