Training must come from the top. Chief editors must be available at the outset to share their industry know-how with promising neophytes. Juniors teaching juniors may be expedient in terms of your time, but it's not the best way to go. Create a systematic training program that takes priority over the usual interruptions. This means that during each of the first 10 days your junior editor is on board, you spend at least one hour in a teaching mode.
Some editors use standard slide shows to facilitate instruction.
Beware of job descriptions that foster industry ignorance. Even some senior editors are now bogged down by job descriptions that chain them to their desks. Field trips are a non-event. Today's alert editors insist that all staff members personally call on readers at least once a month. Subsequently, the staffer must file a written report identifying possible story ideas for future issues.