Even in today's unforgiving environment, some department heads believe that if you're not making mistakes, you must not be trying hard enough. Talk, talk, talk with your junior officers. You cannot put up a wall between yourselves. You have to continue to work on the relationship. Don't pull your punches, but don't let your advice sting.
Nothing teaches like experience.
Sharing those experiences will help junior officers learn how to make their own good decisions. Look for things that can make them do their jobs better. Don't let them get in the habit of procrastinating. Holding them to deadlines will help them become pro-active leaders. Don't make decisions for them.