My approach to self improvement is pretty simple: You and your employees need to keep improving your skills; otherwise you will be left behind. Here is how I approach the topic of figuring out what skills need to be improved in the current role.
Ask yourself what technical, marketing, sales, management/leadership, and/or presentation skills do individuals on the team need and do they have a training plan in place?
Then related to this is the topic of growing your skills in order to get to some career goal. Here is how I approach the topic of figuring out what skills are needed to get to that career goal.
What do you want to do?
What skills are needed to get there?
How do you get those skills?
Then, go get those skills!
Of course, you and/or your employee should have an idea of where they want their career to go. Maybe not a specific job, but a general idea of the type of work is needed before you can start planning out career goals and required skills.