Oh, I forgot, database management techniques.

This is probably the most important for someone going into a Library career.

Honestly, everything else just comes with time. The most useful skill is being able to use and understand The Dewey Decimal system and to be able to interact with it in a database suite like Access or even good old raw SQL.

I hope you know your kid is basically going to be a database manager going this route. It might not be for them.