If you are not aware of GovLoop, check it out. It's the "Knowledge Network for Government" and allows you to "join more than 300,000 of your federal, state and local government peers in innovating and problem-solving with free resources and training."
I recently ran across this good post on their site about five practical resources for new managers. Personally, I think these are good resources for any manager, so I am passing them on to any GIS Managers out there looking for help.
https://www.govloop.com/5-practical-resources-for-new-managers/